16987...14751 (12837064-digits)

This number is a prime.

The third largest known prime number (2^42643801-1); first found by a machine on April 12, 2009. It is odd that no human took notice of this fact however until the following June 4! It is credited to Odd Magnar Strindmo from Melhus, Norway, who has been part of GIMPS since it began. This 47th known Mersenne prime is only 141125 digits (just over 1%) shorter than the largest known prime at that time.