815997 has 32 divisors (see below), whose sum is σ = 1388800. Its totient is φ = 423360.

The previous prime is 815989. The next prime is 816019. The reversal of 815997 is 799518.

It is a happy number.

It is not a de Polignac number, because 815997 - 2³ = 815989 is a prime.

It is a super-2 number, since 2×815997² = 1331702208018, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

Its product of digits (22680) is a multiple of the sum of its prime divisors (84).

815997 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13347 + ... + 13407.

It is an arithmetic number, because the mean of its divisors is an integer number (43400).

2⁸¹⁵⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

815997 is a deficient number, since it is larger than the sum of its proper divisors (572803).

815997 is a wasteful number, since it uses less digits than its factorization.

815997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98 (or 84 counting only the distinct ones).

The product of its digits is 22680, while the sum is 39.

The square root of 815997 is about 903.3255227215. The cubic root of 815997 is about 93.4464600491.

It can be divided in two parts, 8159 and 97, that added together give a triangular number (8256 = T₁₂₈).

The spelling of 815997 in words is "eight hundred fifteen thousand, nine hundred ninety-seven".