New largest prime number discovered

If you have a whole lot of free time, you might be able to type out the largest known prime number.

The newly found number has 23,249,425 digits, nearly one million digits more than the previous record holder, discovered a year ago. Here comes the math: the new prime number is calculated by multiplying together 77,232,917 twos, and then subtracting one.

Because no one, not even a mathematician, has the time to recite 23 million digits, the number was given the not-so-catchy name of M77232917. (But its friends call it 2 to the power of 77,232,917 minus 1.)

A collaborative computer project called the Great Internet Mersenne Prime Search, which has been going on for years, found the number in late December, on a computer volunteered by Tennessee electrical engineer Jonathan Pace. Pace had been hunting for primes for 14 years. Merseene primes are a special class of rare prime numbers named for Jesuit scholar Marin Mersenne, who studied them in the 17th century.