PrimeGrid’s
Primorial Prime Search
On 20 Dec 2010, 08:05:22 UTC, PrimeGrid’s PRPNet found the largest known
Primorial prime:843301#-1
The prime is 365,851 digits long and enters Chris Caldwell's “The Largest Known
Primes Database” (http://primes.utm.edu/primes) ranked 1st for Primorial primes
and 260th overall.
The discovery was made by Michał Gasewicz of Poland using an Intel dual Xeon
E5520 @ 2.27GHz with 12GB RAM, running 64 bit Linux. This computer took about
71 hours and 20 minutes to complete the primality test using pfgw x64. Michał isa member of the BOINC@Poland team.
The prime was verified on 23 Dec 2010, by an Intel Q6600 @ 2.4 GHz with 2 GB
RAM, running 64 bit Windows XP Professional. This computer took a little over 69
hours 19 minutes to complete the primality test using pfgw x64.
The credits for the discovery are as follows:
1. Michał Gasewicz (Poland), discoverer
2. PrimeGrid, et al.
3. fsieve/psieve/fpsieve, sieve programs developed by Mark Rodenkirch andGeoff Reynolds
4. PFGW, primality program developed by Chris Nash & Jim Fougeron
Entry in “The Largest Know Primes Database” can be found here:

http://primes.utm.edu/primes/page.php?id=97061
This is only the 19th known p#-1 Primorial prime and the 1st discovered in 18 years.
It is the 1st found of either form (p#+1, p#-1) in over 9 years. Needless to say,this is an exceptional find. It more than doubles the size of the previous record of392113#+1 (169966 digits).
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 their spare CPU cycles. A special thanks to everyone who offered theiradvice and/or computing power to the search - especially Mark Rodenkirch andGeoff Reynolds who were major forces in moving the project forward. Also, thankyou to all the sievers and PRPNet’ers who contributed to this effort.
The Primorial Prime Search will continue to seek even larger primes. To join thesearch please visit PrimeGrid: http://www.primegrid.com

PrimeGrid’s
Primorial Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius, which
utilizes BOINC and PRPNet to search for primes. PrimeGrid's primary goal is to bringthe excitement of prime finding to the "everyday" computer user. Simply download
the software and let your computer do the rest. Participants can choose from avariety of prime forms to search. With a little patience, you may find a large oreven record breaking prime.
BOINC
The Berkeley Open Infrastructure for Network Computing (BOINC) is asoftware platform for distributed computing using volunteered computerresources. It allows users to participate in multiple distributed computing
projects through a single program. Currently BOINC is being developed by ateam based at the University 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, 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