About
PrimeGrid's primary goal is to advance mathematics by enabling everyday computer users to contribute their system's processing power towards prime finding. By simply
downloading and installing BOINC and attaching to the PrimeGrid project,
participants can choose from a variety of prime forms to search. With a little patience, you may find a large or even record
breaking prime and enter into Chris Caldwell's The Largest Known Primes Database as
a Titan!
PrimeGrid's secondary goal is to provide relevant educational materials about primes. Additionally, we wish to contribute to the
field of mathematics.
Lastly, primes play a central role in the cryptographic systems which are used for computer security. Through the study of prime
numbers it can be shown how much processing is required to crack an encryption code and thus to determine whether current
security schemes are sufficiently secure. PrimeGrid is currently running several sub-projects:
- 321 Prime Search: searching for
mega primes of the form 3·2n±1.
- Cullen-Woodall Search: searching for
mega primes of forms n·2n+1 and
n·2n−1.
- Extended Sierpinski Problem: helping solve the Extended Sierpinski Problem.
- Generalized Fermat Prime Search: searching for
megaprimes of the form b2n+1.
- Prime Sierpinski Project: helping Prime Sierpinski Project solve the Prime Sierpinski Problem.
- Proth Prime Search: searching for primes of the form k·2n+1.
- Seventeen or Bust: helping to solve the Sierpinski Problem.
- Sierpinski/Riesel Base 5: helping to solve the Sierpinski/Riesel Base 5 Problem.
- Sophie Germain Prime Search: searching for primes p and 2p+1.
- The Riesel problem: helping to solve the Riesel Problem.
Recent Significant Primes
On 20 June 2018, 09:48:29 UTC, PrimeGrid's Sierpinski/Riesel Base 5 Problem project (SR5) eliminated k=81556 by finding the base 5 mega prime:
81556·52539960+1
The prime is 1,775,361 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 2 nd for base 5 primes and 61 st overall.
32 k's now remain in the Sierpinski Base 5 Problem.
The discovery was made by Jiří Bočan ( boceli) of the Czech Republic
using an Intel(R) Core(TM) i3-6100 CPU @ 3.70GHz with 4 GB RAM running Microsoft Windows 7 Professional Edition.
This computer took about 4 hours and 23 minutes to complete the primality test using multithreaded LLR.
Jiří is a member of the Czech National Team.
For more information, please see the Official Announcement.
On 19 June 2018, 09:48:29 UTC, PrimeGrid's Sierpinski/Riesel Base 5 Problem project (SR5) eliminated k=327926 by finding the world record base 5 mega prime:
327926·52542838-1
The prime is 1,777,374 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 1 st for base 5 primes and 60 th overall.
71 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Selya Tsuji ( stsuji) of Japan
using an Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz with 32 GB RAM running Microsoft Windows 10 Professional Edition.
This computer took about 39 hours and 36 minutes to complete the primality test using LLR.
Selya is a member of Team 2ch.
For more information, please see the Official Announcement.
On 17 June 2018, 15:40:35 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
5205422262144+1
The prime is 1,760,679 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 8 th for Generalized Fermat primes and 60 th overall.
The discovery was made by Scott Brown ( Scott Brown) of the United States
using an NVidia GeForce GTX 1080 in an Intel(R) Xeon(R) E5-1650 v3 CPU @ 3.50GHz with 32GB RAM, running Windows 7 Enterprise Edition.
This GPU took about 18 minutes to complete the probable prime (PRP) test using GeneferOCL3.
Scott is a member of the Aggie The Pew team.
The PRP was internally confirmed prime by PrimeGrid using an Intel(R) Xeon(R) E3-1240 v6 CPU @ 3.70GHz with 2GB RAM, running Linux.
This computer took about 5 hours and 50 minutes to complete the primality test using multithreaded LLR.
For more information, please see the Official Announcement.
On 5 June 2018, 05:24:10 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
5152128262144+1
The prime is 1,759,508 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 8 th for Generalized Fermat primes and 60 th overall.
The discovery was made by Rob Gahan ( Robish) of Ireland
using an NVIDIA GeForce GTX Titan X in an Intel(R) Core(TM) i7-5930K CPU at 3.50GHz with 32GB RAM, running Windows 10 Core Edition.
This GPU took about 25 minutes to complete the probable prime (PRP) test using GeneferOCL3.
Rob is a member of the Storm team.
The PRP was internally confirmed prime by PrimeGrid using an Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz with 16GB RAM, running Microsoft Windows 10 Professional.
This computer took about 7 hours and 11 minutes to complete the primality test using multithreaded LLR.
For more information, please see the Official Announcement.
Other significant primes
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News 
Another SR5 Mega Prime!
On 20 June 2018, 06:35:42 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=81556 by finding the mega prime:
81556*5^2539960+1
The prime is 1,775,361 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 61st overall. 32 k's now remain in the Sierpinski Base 5 Problem.
The discovery was made by Jiří Bočan (boceli) of the Czech Republic using an Intel(R) Core(TM) i3-6100 CPU @ 3.70GHz with 4 GB RAM running Microsoft Windows 7 Professional Edition. This computer took about 4 hours 23 minutes to complete the primality test using multithreaded LLR. Jiří is a member of the Czech National Team.
The prime was verified on 21 June 2018, 11:41:42 UTC by Wolfgang Schwieger (DeleteNull) of Germany using an Intel(R) Core(TM) i7-7820X CPU @ 3.60GHz with 32 GB RAM running Microsoft Windows 10 Professional Edition. This computer took about 1 hour 11 minutes to complete the primality test using multithreaded LLR. Wolfgang is a member of the SETI.Germany team.
For more details, please see the official announcement.
22 Jun 2018 | 18:40:05 UTC
· Comment
New SR5 Mega Prime!
On 19 June 2018, 09:48:29 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=327926 by finding the mega prime:
327926*5^2542838-1
The prime is 1,777,374 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 60th overall. 71 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Selya Tsuji (stsuji) of Japan using an Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz with 32 GB RAM running Microsoft Windows 10 Professional Edition. This computer took about 39 hours 37 minutes to complete the primality test using LLR. Selya is a member of Team 2ch.
For more details, please see the official announcement.
21 Jun 2018 | 19:03:11 UTC
· Comment
Another GFN-262144 Mega Prime!
On 17 June 2018, 15:40:35 UTC, PrimeGrid’s Generalized Fermat Prime Search found the Generalized Fermat mega prime:
5205422^262144+1
The prime is 1,760,679 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 8th for Generalized Fermat primes and 60th overall.
The discovery was made by Scott Brown (Scott Brown) of the United States using an NVidia GeForce GTX 1080 in an Intel(R) Xeon(R) E5-1650 v3 CPU @ 3.50GHz with 32GB RAM, running Windows 7 Enterprise Edition. This GPU took about 18 minutes to probable prime (PRP) test with GeneferOCL3. Scott is a member of the Aggie The Pew team.
The prime was verified on 17 June 2018, 16:44:04 UTC by Keith Reinhardt (Keith) of Canada using an NVidia GeForce GTX 1050 Ti in an Intel(R) Core(TM) i7-4790 CPU at 3.60GHz with 16GB RAM, running Windows 7 Professional Edition. This GPU took about 43 minutes to probable prime (PRP) test with GeneferOCL5. Keith is a member of the BOINC@Denmark team.
The PRP was confirmed prime by an Intel(R) Xeon(R) E3-1240 v6 CPU @ 3.70GHz with 2GB RAM, running Linux. This computer took about 5 hours 50 minutes to complete the primality test using multithreaded LLR.
For more details, please see the official announcement.
19 Jun 2018 | 15:08:24 UTC
· Comment
GFN-262144 Mega Prime!
On 5 June 2018, 05:24:10 UTC, PrimeGrid’s Generalized Fermat Prime Search found the Generalized Fermat mega prime:
5152128^262144+1
The prime is 1,759,508 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 8th for Generalized Fermat primes and 60th overall.
The discovery was made by Rob Gahan (Robish) of Ireland using an NVIDIA GeForce GTX Titan X in an Intel(R) Core(TM) i7-5930K CPU at 3.50GHz with 32GB RAM, running Windows 10 Core Edition. This GPU took about 25 minutes to probable prime (PRP) test with GeneferOCL3. Rob is a member of the Storm team.
The prime was verified on 5 June 2018, 05:43:47 by Aaron Houston Clinton (denim) of the United States using an NVIDIA GeForce GTX 1080 Ti GPU in an Intel(R) Core(TM) i7-6700K CPU at 4.00GHz with 16GB RAM, running Windows 10 Professional Edition. This GPU took about 13 minutes to probable prime (PRP) test with GeneferOCL3. Aaron is a member of the SETI.USA team.
The PRP was confirmed prime by an Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz with 16GB RAM, running Microsoft Windows 10 Professional. This computer took about 7 hours 11 minutes to complete the primality test using LLR.
For more details, please see the official announcement.
6 Jun 2018 | 21:39:58 UTC
· Comment
Do not use Nvidia driver 397.31
It has come to my attention that Nvidia recently released a new video driver that is causing widespread problems. 397.31 seems to cause the GPU to become inaccessible to both CUDA and OpenCL programs after a while, and can only be reset by rebooting the computer. It's likely this affects all BOINC projects and not just PrimeGrid. Indeed, it probably affects all GPU programs, even those that don't run under BOINC. There's a newer, hotfix driver 397.55 which seems to correct the problem. I strongly recommend either upgrading to 397.55 or rolling back to a driver earlier than 397.31.
More information can be found here.
6 May 2018 | 13:26:37 UTC
· Comment
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Newly reported primes(Mega-primes are in bold.)
1149*2^2593359+1 (fax); 1503*2^1494985+1 (Randall J. Scalise); 94191588^32768+1 (Johny); 40374324^65536+1 (alnitak2019); 52043532^131072+1 (Dirk); 40348160^65536+1 (CGB); 4012959988497*2^1290000-1 (usverg); 81556*5^2539960+1 (boceli); 93970766^32768+1 (xss); 327926*5^2542838-1 (stsuji); 4299*2^1494233+1 (Grzegorz Roman Granowski); 5205422^262144+1 (Scott Brown); 51954384^131072+1 (Robish); 4010077409835*2^1290000-1 (tazzduke); 93822920^32768+1 (Fire$torm [BlackOps]); 1171*2^2595736+1 (Randall J. Scalise); 93768930^32768+1 (Adrian Schori); 4008014234385*2^1290000-1 (Bernd Mollerus); 4006854424527*2^1290000-1 (Kai Ylijoki); 51872628^131072+1 (DeleteNull) Last 24 hoursTop participants by work done in the last 24 hours | Top teams by work done in the last 24 hours |
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