A new Mersenne prime has been found with the assistance of distributed computing:
A computer professional in Norway, with the help of an online computing project, has discovered a new Mersenne prime. This sought-after number represents the 47th Mersenne prime discovered since ancient Greek mathematicians first uncovered them. (See the NPR story for details)
A Mersenne prime is a positive integer satisfying the following equation while also being prime:
$$ M_n=2^n-1.\ $$
n must be prime too, as a matter of consequence.
The new number is about 13 million digits long and would require 3,461 pages to display the number in base 10 with 75 digits per line and 50 lines per page.