ACM News 08/02/2013
The largest known prime number is more than 17 million digits long. Discovered by University of Central Missouri mathematician Curtis Cooper, the 48th known Mersenne prime is 2 [57,885,161] minus 1. The number would span more than 30 miles if it were typed out in a standard Times Roman 12-point font. Moreover, it would fill more than six Bibles. Cooper made the discovery on Jan. 25, according to the Great Internet Mersenne Prime Search, which uses a grid of computers provided by volunteers to find large prime numbers. The grid that Cooper used had 360,000 central processing units peaking at 150 trillion calculations per second. The new Mersenne prime number was verified in independent testing using different programs running on different hardware. One test lasted 3.6 days and used a NVIDIA graphics processing unit, while another used an Intel Core i7 CPU and lasted 4.5 days.
More info: Computerworld (02/05/13) Sharon Gaudin