5209

5209 is a prime number.

5209 is the largest minimal prime in base 6 (40041).

The reversal of 5209 is a square (9025 = 95²) (A007488).

5209 is the lower prime of a difference of 18 between consecutive primes (A031936). It is also the first of two consecutive primes with equal digital sums (A066540): 5 + 2 + 0 + 9 = 16 and 5 + 2 + 2 + 7 = 16.

5209 has a representation as a sum of two squares: 5209 = 5² + 72².

5209 is the hypotenuse of a primitive Pythagorean triple: 5209² = 720² + 5159².

5209 is a divisor of 35¹⁴ - 1.

Source: Prime Curios!