865856 has 28 divisors (see below), whose sum is σ = 1749552. Its totient is φ = 425088.

The previous prime is 865847. The next prime is 865859. The reversal of 865856 is 658568.

It is a super-2 number, since 2×865856² = 1499413225472, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (865859) 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, 5231 + ... + 5393.

It is an arithmetic number, because the mean of its divisors is an integer number (62484).

2⁸⁶⁵⁸⁵⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 865856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (874776).

865856 is an abundant number, since it is smaller than the sum of its proper divisors (883696).

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

865856 is a wasteful number, since it uses less digits than its factorization.

865856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258 (or 248 counting only the distinct ones).

The product of its digits is 57600, while the sum is 38.

The square root of 865856 is about 930.5138365441. The cubic root of 865856 is about 95.3122137947.

The spelling of 865856 in words is "eight hundred sixty-five thousand, eight hundred fifty-six".