PrimeGrid’s
27121 Prime Search
On 9 March 2015, 17:49:18, PrimeGrid’s 27121 Prime Search, through PRPNet and incollaboration with the 12121 Search (k=27 sister project), has found the mega prime:
27*25213635+1
The prime is 1,569,463 digits long and will enter Chris Caldwell's “The Largest Known
Primes Database” (http://primes.utm.edu/primes) ranked 38th overall.
The discovery was made by Hiroyuki Okazaki of Japan using an Intel(R) Xeon(R) CPU
E5-2648L 0 @ 1.80GHz Processor with 64GB RAM, running Microsoft Windows 7Ultimate. This computer took about 5 hours 5 minutes to complete the primality test
using LLR. Hiroyuki is a member of the Aggie The Pew team.
The prime was verified internally.
Credits for the discovery are as follows:


Hiroyuki Okazaki (Japan), discoverer
PrimeGrid, et al.
Srsieve, sieving program developed by Geoff Reynolds
PSieve, sieving program developed by Ken Brazier and Geoff Reynolds
LLR, primality program developed by Jean Penné

Entry in “The Largest Know Primes Database” can be found here:
http://primes.utm.edu/primes/page.php?id=119539
PrimeGrid’s 27121 Prime Search is a collaboration with the 12121 Search, which wasestablished on 5/24/2004 to search for large primes of the form 121*2^n-1. Later, on
3/1/2005, they added k=27 to their search. Their "short term" goal is to search for n up
to 10M. PrimeGrid added the +1 form and searches both k’s and forms together.
Fermat number divisibility (including generalized and extended) was checked byOpenPFGW using the following settings: -gxo -q27*2^5213635+1. For more
information about Fermat and generalized Fermat number divisors, please see Wilfrid
Keller's sites: http://www.prothsearch.net/fermat.html
 http://www.prothsearch.net/GFNfacs.html
27*2^5213635+1 is a Factor of xGF(5213634,7,6)
27*2^5213635+1 is a Factor of GF(5213633,8)
Using a single PC would have taken years to find this prime. So this timely discovery
would not have been possible without the thousands of volunteers who contributed
their spare CPU cycles. A special thanks to everyone who contributed their advice
and/or computing power to the search - especially all the sievers who work behind thescenes to make a find like this possible.
The 27121 Prime Search will continue to seek even larger primes. To join the searchplease visit PrimeGrid: http://www.primegrid.com

PrimeGrid’s
27121 Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius, Lennart
Vogel, and John Blazek, which utilizes BOINC and PRPNet to search for primes.
PrimeGrid's primary goal is to bring the excitement of prime finding to the "everyday"
computer user. Simply download the software and let your computer do the rest.
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.
BOINCThe Berkeley Open Infrastructure for Network Computing (BOINC) is a software
platform for distributed computing using volunteered computer resources. It
allows users to participate in multiple distributed computing projects through asingle program. Currently BOINC is being developed by a team based at theUniversity of California, Berkeley led by David Anderson.
This platform currently supports projects from biology to math to astronomy. For
more information, please visit BOINC: http://boinc.berkeley.edu
PRPNet
PRPNet is a client/server application written by Mark Rodenkirch that is
specifically designed to help find prime numbers of various forms. It is easily
ported between various OS/hardware combinations. PRPNet does not run each
PRP test itself, but relies on helper programs, such as LLR, PFGW, phrot, wwww,and genefer to do the work.
For more information, please visit PrimeGrid’s PRPNet forum thread:
http://www.primegrid.com/forum_thread.php?id=1215
For more information about PrimeGrid and a complete list of available prime search
projects, please visit: http://www.primegrid.com