On 22 November 2014, 14:46:02 UTC, PrimeGrid’s 321 Prime Search project found the mega prime:

3*2^11484018-1

The prime is 3,457,035 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 12th overall. This is the largest known 321 mega prime and the largest prime found to date at PrimeGrid!

The discovery was made by Serhiy Gushchak (Sergyg) of the Ukraine using an Intel(R) Core(TM) i3-2120 CPU @ 3.30GHz with 12 GB RAM running Microsoft Windows 7 Ultimate. This computer took about 27 hours and 2 minutes to complete the primality test using LLR. Serhiy is a member of the Ukraine Team.

The prime was verified on 24 November 2014 11:24:03 UTC, by Thomas Schulze Curly of Germany using an Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz with 16 GB RAM running Microsoft Windows 7 Professional. This computer took about 32 hours and 56 minutes to complete the primality test using LLR. Thomas is a member of the BOINCStats Team.

For more details, please see the official announcement.

My apologies for the delay in the announcement and my hearty congratulations to Serhiy on the terrific find!

Some interesting facts about this find:

This is the largest known 321 prime, and the largest prime ever found by PrimeGrid.

This was PrimeGrid's 28th mega prime discovery of 2014 (a new record) and our 66th mega prime overall.

November is the 11th consecutive month this year where PrimeGrid has found at least one mega prime, and the 12th consecutive month in a row that we've found at least one mega prime going back to December of 2013.

Does anyone know the root of the inconsistency between this which is claimed to be our 66th megaprime, and this list, which contains only 65 primes?

- Iain
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Twitter: IainBethune
Proud member of team "Aggie The Pew". Go Aggie!
3073428256125*2^1290000-1 is Prime!

Does anyone know the root of the inconsistency between this which is claimed to be our 66th megaprime, and this list, which contains only 65 primes?

- Iain

Update: The extra prime in our list is 7*2^3511774+1 (#52 on our list), which is on the Top 5K list without crediting PrimeGrid. Either it was discovered elsewhere and we didn't know about it and "re-discovered" it, or it was found here and the person reported it themselves without giving PrimeGrid credit.

It's difficult to tell which is correct.

EDIT: Or *we* reported it for the user, and we didn't give PrimeGrid credit. If it was indeed done on PrimeGrid, it was at the very beginning of our existence and things surely operated differently then than they do now.

EDIT 2: This prime is one of the really old "PRPNet" primes that I imported a few years ago from the old log files Lennart and John had.
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My lucky number is 75898⁵²⁴²⁸⁸+1

After even more research, looking through all the files I've got, my notes, and so forth, that particular prime is one of about 400 or so PRPNet primes that were manually put into the BOINC database before I did the mass import. The bottom line is I have no idea what the origin of that prime is, who put it into the database, and whether or not this was found by the same person as is listed in the Top 5K database.
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My lucky number is 75898⁵²⁴²⁸⁸+1

Why an i3 took hours less than an i7 to double check the same prime?

CPU type GenuineIntel
Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz [Family 6 Model 58 Stepping 9]
Number of processors 8

Michael is right... :)
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92*10^^1439761-1 NEAR-REPDIGIT PRIME :) :) :)
4 * 650^⁴⁹⁸¹⁰¹-1 CRUS PRIME
314187728^¹³¹⁰⁷²+1 GENERALIZED FERMAT
Proud member of team Aggie The Pew. Go Aggie!