9689

This number is a prime.

The only known multidigit Mersenne prime exponent that starts and ends with the same composite digit. [Luhn]

2⁹⁶⁸⁹ - 1 is the largest (as of August 2002) known Mersenne prime with a prime number of digits (2917). [Rupinski]

The sequence of digits '9689' appears exactly once in the Mersenne prime 2^9689 - 1. [Harrison]

M(9689) begins a run of seven consecutive Mersenne primes that end with the decimal digit 1. [Honaker]