817

817 = 19 x 43.

817 is a centered hexagonal (hex) number (A003215).

817 is the sum of three consecutive prime numbers: 817 = 269 + 271 + 277.

817 has the representation 817 = 3⁶ + 88.

The sum of the even digits of 817 equals the sum of the odd digits of 817 (A036301).

817 is a number n such that 1 + n² + n⁴ + n⁶ + n⁷ is a prime (A126908).

Source: On-Line Encyclopedia of Integer Sequences