Mersenne primes are of the form 2ⁿ - 1

This is to say that it is a prime number which is one less than a power of two. They are named after Marin Mersenne, a French Minim friar, who studied them in the early 17th century.

As of October 2014, 48 Mersenne primes are known. The largest known prime number 2^57,885,161 - 1 is a Mersenne prime.

The asteroid with minor planet number 8191 is named 8191 Mersenne after Marin Mersenne, because 8191 is a Mersenne prime (3 Juno, 7 Iris, 31 Euphrosyne and 127 Johanna having been discovered and named during the 19th century).

Because of the scarcity of Mersenne Prime Days during our lifetimes, we offer the opportunity to celebrate Mersenne Prime Exponent Days.