173

173 is a prime number. It is a Sophie Germain prime because 2 x 173 + 1 = 347, which is also prime.

173 has a representation as a sum of two squares: 173 = 2² + 13². It is the sum of the squares of two Fibonacci numbers, 2 and 13.

173 is the hypotenuse of a primitive Pythagorean triple: 173² = 52² + 165².

173 is the only prime whose sum of cubed digits equals its reversal: 1³ + 7³ + 3³ = 371.

173 is the largest known prime whose square (29929) and cube (5177717) have no digits in common.

173 = 1 + 2² + 2³ + 2⁵ + 2⁷, where the exponents are consecutive primes.

In the 1993 movie The Sandlot, The Beast (a ferocious dog) is said to have eaten 173 guys.

Source: Prime Curios!