October 1, 2008 at Largest prime number
Its size is breathtaking! With a length of about 13 million characters, this 45th Mersenne prime makes the number of atoms in the known universe an insignificant quantity, with their “only 80-digit number.” The shape of the Mersenne prime is beautiful and smart: 2 n -1, where n is a prime. The sequence of Mersenne numbers begins as follows: 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, ... (sequence A000225 in OEIS).
Mersenne primes are the largest primes known to science. The previous world record belonged to the number 232582657-1, having 9.808.358 categories.
The last, the 44th, was found two years ago, and the current one was in early autumn . No hope of writing this number: 2 43,112,609-1 would take many kilometers in length. I think you can imagine what 13 mb of numbers alone are.
via science news