865816 has 16 divisors (see below), whose sum is σ = 1855440. Its totient is φ = 371040.

The previous prime is 865807. The next prime is 865817. The reversal of 865816 is 618568.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7675 + ... + 7786.

It is an arithmetic number, because the mean of its divisors is an integer number (115965).

2⁸⁶⁵⁸¹⁶ is an apocalyptic number.

It is an amenable number.

865816 is an abundant number, since it is smaller than the sum of its proper divisors (989624).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

865816 is a wasteful number, since it uses less digits than its factorization.

865816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15474 (or 15470 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 865816 is about 930.4923427949. The cubic root of 865816 is about 95.3107460575.

It can be divided in two parts, 865 and 816, that added together give a square (1681 = 41²).

The spelling of 865816 in words is "eight hundred sixty-five thousand, eight hundred sixteen".