See http://www.mersenne.org/various/57885161.htm

GIMPS Project Discovers Largest Known Prime Number, 257,885,161-1 [2 to the 57885161 th power minus 1]

ORLANDO, Florida -- On January 25th at 23:30:26 UTC, the largest known prime number, 257,885,161-1, was discovered on Great Internet Mersenne Prime Search (GIMPS) volunteer Curtis Cooper's computer. The new prime number, 2 multiplied by itself 57,885,161 times, less one, has 17,425,170 digits.  With 360,000 CPUs peaking at 150 trillion calculations per second, 17th-year GIMPS is the longest continuously-running global "grassroots supercomputing"[1] project in Internet history.

Dr. Cooper is a professor at the University of Central Missouri. This is the third record prime for Dr. Cooper and his University. Their first record prime was discovered in 2005, eclipsed by their second record in 2006. Computers at UCLA broke that record in 2008 with a 12,978,189 digit prime number. UCLA held the record until University of Central Missouri reclaimed the world record with this discovery. The new primality proof took 39 days of non-stop computing on one of the university's PCs.  Dr. Cooper and the University of Central Missouri are the largest individual contributors to the project. The discovery is eligible for a $3,000 GIMPS research discovery award.

See more at http://www.mersenne.org/various/57885161.htm

[1]Science (American Association for the Advancement of Science), May 6, 2005 p 810.

Jerry P. Becker
Dept. of Curriculum & Instruction
Southern Illinois University
625 Wham Drive
Mail Code 4610
Carbondale, IL  62901-4610
Phone:  (618) 453-4241  [O]
            (618) 457-8903  [H]
Fax:      (618) 453-4244
E-mail:   jbecker@siu.edu