865664 has 16 divisors (see below), whose sum is σ = 1724820. Its totient is φ = 432768.

The previous prime is 865661. The next prime is 865681. The reversal of 865664 is 466568.

It is a tau number, because it is divible by the number of its divisors (16).

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3254 + ... + 3509.

2⁸⁶⁵⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

865664 is a deficient number, since it is larger than the sum of its proper divisors (859156).

865664 is an equidigital number, since it uses as much as digits as its factorization.

865664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6777 (or 6765 counting only the distinct ones).

The product of its digits is 34560, while the sum is 35.

The square root of 865664 is about 930.4106620197. The cubic root of 865664 is about 95.3051682437.

The spelling of 865664 in words is "eight hundred sixty-five thousand, six hundred sixty-four".