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 29 June 2019, 00:54:18 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
2877652524288+1
The prime is 3,386,397 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 3 rd for Generalized Fermat primes and 26 th overall.
The discovery was made by Roman Vogt ( Tabaluga) of Germany
using an NVIDIA GeForce GTX 1060 in an Intel(R) Core(TM) i7-2700K CPU @ 3.50GHz CPU with 16GB RAM, running Windows 10.
This computer took about 1 hour and 42 minutes to probable prime (PRP) test with GeneferOCL5.
Roman is a member of the Sicituradastra. team.
The PRP was confirmed prime by an Intel(R) Xeon(R) CPU E3-1240 v6 @ 3.70GHz with 4GB RAM, running Linux. This computer took about 25 hours 53 minutes to complete the primality test using multithreaded LLR.
For more information, please see the Official Announcement.
On 23 June 2019, 14:39:48 UTC, PrimeGrid's Sierpiński/Riesel Base 5 Problem project eliminated k=322498 by finding the mega prime:
322498·52800819-1
The prime is 1,957,694 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 63 rd overall and is the largest known base 5 prime. 67 k's now remain in the Riesel Base 5 problem.
The discovery was made by Jordan Romaidis of the United States
using an Intel(R) Xeon(R) Gold 5120 CPU @ 2.20GHz with 96GB RAM running Microsoft Windows 10 Enterprise x64 Edition.
This computer took about 25 hours and 28 minutes to primality test using multithreaded LLR.
Jordan is a member of the San Francisco team.
For more information, please see the Official Announcement.
On 21 June 2019, 01:30:42 UTC, PrimeGrid's Sierpiński/Riesel Base 5 Problem project eliminated k=88444 by finding the mega prime:
88444·52799269-1
The prime is 1,956,611 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 63 rd overall and is the largest known base 5 prime. 68 k's now remain in the Riesel Base 5 problem.
The discovery was made by Scott Brown of the United States
using an Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz with 32GB RAM running Microsoft Windows 10 Professional x64 Edition.
This computer took about 5 hours and 29 minutes to primality test using multithreaded LLR.
Scott is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
Other significant primes
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News 
50th Anniversary of the Moon Landing Challenge starts July 15th 20:17 UTC
"Thirty seconds and counting. Astronauts report it feels good. T-25 seconds. Twenty seconds and counting. T-15 seconds, guidance is internal. 12, 11, 10, 9 ... ignition sequence start ... 6, 5, 4, 3, 2, 1, 0 ... All engines running. Liftoff! We have a liftoff ... 32 minutes past the hour, liftoff on Apollo 11!"
To celebrate the 50th Anniversary of humans landing on the Moon, PrimeGrid is running a 5 day challenge from July 15th 2019, 20:17 UTC until July 20th, 20:17 UTC.
Work units from the PPS (LLR) project, which are downloaded and completed during the challenge will count towards your challenge score. Many primes are expected to be found.
For more information and discussion, please see the official challenge thread: http://www.primegrid.com/forum_thread.php?id=8635
15 Jul 2019 | 10:42:14 UTC
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GFN-524288 Mega Prime!
On 29 June 2019, 00:54:18 UTC, PrimeGrid’s Generalized Fermat Prime Search found the Generalized Fermat mega prime:
2877652^524288+1
The prime is 3,386,397 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 3rd for Generalized Fermat primes and 26th overall.
The discovery was made by Roman Vogt (Tabaluga) of Germany using an NVIDIA GeForce GTX 1060 in an Intel(R) Core(TM) i7-2700K CPU @ 3.50GHz CPU with 16GB RAM, running Windows 10. This GPU took about 1 hour and 42 minutes to probable prime (PRP) test with GeneferOCL5. Roman is a member of the Sicituradastra. team.
The PRP was verified on 29 June 2019, 08:52:47 by Carlo Villa (carlo) using an NVIDIA GeForce 830M in an Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz with 8GB RAM, running Windows 10. This GPU took about 16 hours and 55 minutes to probable prime (PRP) test with GeneferOCL5.
The PRP was confirmed prime by an Intel(R) Xeon(R) CPU E3-1240 v6 @ 3.70GHz with 4GB RAM, running Linux. This computer took about 25 hours 53 minutes to complete the primality test using multithreaded LLR.
For more details, please see the official announcement.
8 Jul 2019 | 12:20:47 UTC
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Another New SR5 Mega Prime!
On 23 June 2019, 14:39:48 UTC, PrimeGrid’s Sierpiński/Riesel Base 5 Problem project eliminated k=322498 by finding the mega prime:
322498*5^2800819-1
The prime is 1,957,694 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 63rd overall and is the largest known base 5 prime. 67 k’s now remain in the Riesel Base 5 problem.
The discovery was made by Jordan Romaidis of the United States using an Intel(R) Xeon(R) Gold 5120 CPU @ 2.20GHz with 96GB RAM running Microsoft Windows 10 Enterprise x64 Edition. This computer took 25 hours and 28 minutes to complete the primality test using multithreaded LLR. Jordan is a member of the San Francisco team.
The prime was verified on 24 June 2019, 20:59:33 UTC by Scott Brown of the United States using an AMD FX(tm)-8350 Eight-Core Processor with 16GB RAM running Microsoft Windows 10 Core x64 Edition. This computer took about 53 hours and 51 minutes to complete the primality test using multithreaded LLR. Scott is a member of the Aggie The Pew team.
For more details, please see the official announcement.
28 Jun 2019 | 20:11:13 UTC
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New SR5 Mega Prime!
On 21 June 2019, 01:30:42 UTC, PrimeGrid’s Sierpiński/Riesel Base 5 Problem project eliminated k=88444 by finding the mega prime:
88444*5^2799269-1
The prime is 1,956,611 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 63rd overall and is the largest known base 5 prime. 68 k’s now remain in the Riesel Base 5 problem.
The discovery was made by Scott Brown of the United States using an Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz with 32GB RAM running Microsoft Windows 10 Professional x64 Edition. This computer took 5 hours and 29 minutes to complete the primality test using multithreaded LLR. Scott is a member of the Aggie The Pew team.
The prime was verified on 21 June 2019, 14:50:01 UTC by Dave Sunderland (DaveSun) using an Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz with 16GB RAM running Microsoft Windows 10 Core x64 Edition. This computer took about 12 hours and 32 minutes to complete the primality test using multithreaded LLR.
For more details, please see the official announcement.
28 Jun 2019 | 19:55:53 UTC
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AVX-512 Now Supported by LLR
All of PrimeGrid's LLR applications now support AVX-512 on CPUs with that capability. Those of you that have been using app_info.xml/anonymous platform to run LLR 3.8.23 may now use the stock app if you wish, which is also LLR 3.8.23.
UPDATE May 22nd: It has come to my attention that while CPUs with 2 AVX-512 execution units gain a substantial boost in performance, mid-range CPUs with only 1 AVX-512 execution unit may see a significant decrease in performance with the new LLR app. Obviously, this is not intended. For the time being there is no workaround for this. If you have a CPU that supports AVX-512, but has only a single AVX-512 execution unit, you may want to use the anonymous platform mechanism (app_info.xml) to run the older version of LLR. With a challenge starting tomorrow, we won't make changes to the app until at least a week. We apologize for any inconvenience this may cause.
UPDATE May 23rd: I've included a list of single and dual unit AVX-512 CPUs here.
22 May 2019 | 0:22:04 UTC
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Newly reported primes(Mega-primes are in bold.)
485*2^2778151+1 (Honza); 1129*2^2774934+1 (pschoefer); 1023*2^2772512+1 (dthonon); 1171*2^2768112+1 (Scott Cox); 441*2^2754188+1 (joe carnivore); 133254120^32768+1 (vaughan); 437*2^2769299+1 (zunewantan); 133260836^32768+1 (vaughan); 4558538363115*2^1290000-1 (ReaDy); 133173648^32768+1 (vaughan); 133172694^32768+1 (Johny); 701*2^2750267+1 (bcavnaugh); 745*2^2761514+1 (Scott Brown); 537*2^2755164+1 (Randall J. Scalise); 893*2^2758841+1 (JG4KEZ(Koichi Soraku)); 64297742^65536+1 (DaveSun); 337*2^2750860+1 (FishFry); 467*2^2749195+1 (Honza); 3773*2^1542593+1 (Damian); 591*2^2748315+1 (Spear) 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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