865385856 has 320 divisors, whose sum is σ = 2843596800. Its totient is φ = 260029440.

The previous prime is 865385849. The next prime is 865385861. The reversal of 865385856 is 658583568.

865385856 is a `hidden beast` number, since 8 + 6 + 53 + 8 + 585 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 4530721 + ... + 4530911.

It is an arithmetic number, because the mean of its divisors is an integer number (8886240).

Almost surely, 2^865385856 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 865385856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1421798400).

865385856 is an abundant number, since it is smaller than the sum of its proper divisors (1978210944).

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

865385856 is a wasteful number, since it uses less digits than its factorization.

865385856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259 (or 238 counting only the distinct ones).

The product of its digits is 6912000, while the sum is 54.

The square root of 865385856 is about 29417.4413571269. The cubic root of 865385856 is about 952.9495974080.

The spelling of 865385856 in words is "eight hundred sixty-five million, three hundred eighty-five thousand, eight hundred fifty-six".