Chükö

emirp numbers

An emirp is a prime number that becomes a different prime when its decimal digits are reversed.

The first few emirp numbers are: 13, 17, 31, 37, 71, 73, 79, 97, 107, 113, 149, 157, …

11,184 of the first one million positive integers are emirp.

Learn more about emirp numbers on wikipedia.

See other features.