Subtracting from 817 its reverse (718), we obtain a palindrome (99).
817 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 718 = 2 ⋅359.
It is a cyclic number.
It is a Duffinian number.
It is a plaindrome in base 7 and base 13.
It is a nialpdrome in base 16.
It is a self number, because there is not a number n which added to its sum of digits gives 817.
817 is the 17-th hex number.
It is an amenable number.
817 is a wasteful number, since it uses less digits than its factorization.
817 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 62.
The square root of 817 is about 28.5832118559. The cubic root of 817 is about 9.3484731605.