136

This number is a composite.

The sum of all prime factors of 136 is equal to the reversal of π(136). [Cramer]

136 is the first sum of squares (a^2 + b^2), where both a and b have more than one prime factor. [Hunter]

The smallest three-digit number such that the absolute difference between any two digits is prime. Note that these differences create the only three-digit prime containing all three of the first three prime digits. [Loungrides]

The smallest Hoax number whose the reversal is prime. [Loungrides]