865831 has 4 divisors (see below), whose sum is σ = 872200. Its totient is φ = 859464.

The previous prime is 865829. The next prime is 865847. The reversal of 865831 is 138568.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 865831 - 2¹ = 865829 is a prime.

It is a super-2 number, since 2×865831² = 1499326641122, which contains 22 as substring.

It is the 931-st Hogben number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 865793 and 865802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865801) by changing a digit.

It is a nontrivial repunit in base 930.

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 3 ways as a sum of consecutive naturals, for example, 2976 + ... + 3253.

It is an arithmetic number, because the mean of its divisors is an integer number (218050).

2⁸⁶⁵⁸³¹ is an apocalyptic number.

865831 is the 589-th centered pentagonal number.

865831 is a deficient number, since it is larger than the sum of its proper divisors (6369).

865831 is a wasteful number, since it uses less digits than its factorization.

865831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6368.

The product of its digits is 5760, while the sum is 31.

The square root of 865831 is about 930.5004030090. The cubic root of 865831 is about 95.3112964642.

The spelling of 865831 in words is "eight hundred sixty-five thousand, eight hundred thirty-one".