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# 9689

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

2^{9689} - 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]

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