11

This number is a prime.

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

2^^n-9 = 2^(2^(2^...(2^2)..))-9 is divisible by 11 for all sufficiently large n. 11 is the largest prime less than a million of which this is true. [Hartley]

Submitted: 2003-04-07 09:15:07; Last Modified: 2008-01-30 17:28:00.