213466917 - 1 is the first prime number to be found to have more digits than the year it was discovered squared, i.e., more than 20012. [Luhn]
Click here for information on the 39th Mersenne prime.
The largest known Mersenne prime exponent that is an emirp. Note that the sum of its digits is also an emirp. [Loungrides]
The Mersenne prime 2^13466917-1 is a 4053946-digit self-number. It is the the third largest known (or so) prime
self-number as of March 2019. [Kontobesar]