61

This number is a prime.

Single Curio View: (Seek other curios for this number)

61 is the smallest number m and only two-digit number m such that the reversal of concatenation of the first m natural numbers is prime. [Firoozbakht]

Submitted: 2004-06-24 15:23:53; Last Modified: 2008-01-30 17:28:00.