613

Properties:

613 has a representation as a sum of 2 squares:\n613 = 17^2+18^2
613 is an odd number.
613 is an irregular prime, it divides the numerator of the Bernoulli number B_522.
613 is the hypotenuse of a primitive Pythagorean triple:\n613^2 = 35^2+612^2
613 has the representation 613 = 5^4-12.
613 divides 65^3-1.