This isn’t a Mersenne prime. https://www.ams.org/journals/mcom/2002-71-238/S0025-5718-01-01319-9/S0025-5718-01-01319-9.pdf https://www.ams.org/journals/mcom/20

This isn’t a Mersenne prime. https://www.ams.org/journals/mcom/2002-71-238/S0025-5718-01-01319-9/S0025-5718-01-01319-9.pdf https://www.ams.org/journals/mcom/2002-71-238/S0025-5718-01-... says “The Repunit R49081 = (10⁴⁹⁰⁸¹ − 1)/9 is a probable prime.”, so we’re talking numbers that get written as all ones in decimal, not binary.