865881 has 24 divisors (see below), whose sum is σ = 1347840. Its totient is φ = 534336.

The previous prime is 865877. The next prime is 865889. The reversal of 865881 is 188568.

It is not a de Polignac number, because 865881 - 2² = 865877 is a prime.

It is a super-2 number, since 2×865881² = 1499499812322, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9685 + ... + 9773.

It is an arithmetic number, because the mean of its divisors is an integer number (56160).

2⁸⁶⁵⁸⁸¹ is an apocalyptic number.

It is an amenable number.

865881 is a deficient number, since it is larger than the sum of its proper divisors (481959).

865881 is a wasteful number, since it uses less digits than its factorization.

865881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165 (or 162 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 865881 is about 930.5272698852. The cubic root of 865881 is about 95.3131311075.

The spelling of 865881 in words is "eight hundred sixty-five thousand, eight hundred eighty-one".