PrimeGridʼsPrimorial Prime Search
On 28 February 2012, PrimeGrid’s Primorial Prime Search project, through PRPNet,
found the largest known Primorial prime:
1098133#-1
The prime is 476,311 digits long and will enter Chris Caldwell's “The Largest Known
Primes Database” (http://primes.utm.edu/primes) ranked 1st for Primorial primes and253rd overall.
The discovery was made by James P. Burt of the Cayman Islands using an AMD
Phenom 9750 Quad-Core @ 2.4GHz with 4 GB RAM running Windows 7 Professional
x64. This computer took 6 days 10 hours 44 minutes to complete the primality test
using pfgw64. James is a member of the Aggie The Pew team.
The prp was verified on 28 February 2012, by an Intel i5 @ 2.8 GHz with 4 GB RAM,running Max OS X. This computer took a little over 2 hours 55 minutes to complete theprp test using pfgw x64. The prp was confirmed prime on 1 March 2012, by an Intel
Core i7 2600k @3.4Ghz with 8 GB RAM, running Windows 7 x64. This computer took
41 hours 42 minutes to complete the primality test using pfgw x64 AVX.
Credits for the discovery are as follows:
1. James P. Burt (Cayman Islands), discoverer
2. PrimeGrid, et al.
3. fsieve/psieve/fpsieve, sieve programs developed by Mark Rodenkirch andGeoff Reynolds
4. OpenPFGW, a primality program developed by Chris Nash & Jim Fougeron
with maintenance and improvements by Mark Rodenkirch
Entry in “The Largest Know Primes Database” can be found here:
http://primes.utm.edu/primes/page.php?id=105273
This is only the 20th known p#-1 Primorial prime and the 2nd discovered in the last 20years. p#-1 (p primorial minus one) is the product of the primes less than or equal to p.
For example, 13# = 2*3*5*7*11*13. By itself, this cannot be prime so that is why a +1
or -1 is added to the form.
Using a single PC would have taken years to find this prime. So this timely discovery
would not have been possible without the hundreds of volunteers who contributed theirspare CPU cycles. A special thanks to everyone who offered their advice and/or
computing power to the search - especially Mark Rodenkirch and Geoff Reynolds who
were major forces in moving the project forward. Also, thank you to all the sievers andPRPNet’ers who contributed to this effort.
The Primorial Prime Search will continue to seek even larger primes. To join the searchplease visit PrimeGrid: http://www.primegrid.com

PrimeGridʼs
Primorial 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.
BOINC
The 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