Mathematicians at the Univ. of Central Missouri have identified the largest prime number yet, but good luck remembering it.

The university says that a group led by computer science and mathematics professor Curtis Cooper found the 17 million-digit prime number last month. It is the 48^{th} known Mersenne prime and is the third discovered at the 11,800-student university in Warrensburg, about 50 miles east of Kansas City.

Primes are numbers such as 3, 7 and 11 that are divisible only by themselves and 1 without leaving a remainder.

Mersenne primes are named after the 17^{th} century French mathematician who discovered them, Marin Mersenne. They're expressed as 2P-1, or two to the power of "P'' minus one. P is itself a prime number. For the new prime, P is 57,885,161.

The number was independently verified using different programs running on different hardware, according to the Great Internet Mersenne Prime Search, or GIMPS, a cooperative in which underused computing power is harnessed to perform the calculations needed to find and verify Mersenne primes.

The university, which is affiliated with the worldwide computing project, used about 1,000 campus computers in its search. Special software allows students to check email and write papers on campus computers while the machines' excess computing capacity searches for the elusive numbers.