865800864 has 72 divisors (see below), whose sum is σ = 2466015552. Its totient is φ = 288144000.

The previous prime is 865800847. The next prime is 865800893. The reversal of 865800864 is 468008568.

865800864 is a `hidden beast` number, since 8 + 6 + 580 + 0 + 8 + 64 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×865800864² = 1499222272206292992, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 214287 + ... + 218289.

It is an arithmetic number, because the mean of its divisors is an integer number (34250216).

Almost surely, 2^865800864 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 865800864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1233007776).

865800864 is an abundant number, since it is smaller than the sum of its proper divisors (1600214688).

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

865800864 is a wasteful number, since it uses less digits than its factorization.

865800864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4770 (or 4759 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 45.

The square root of 865800864 is about 29424.4942862235. The cubic root of 865800864 is about 953.1019065393.

The spelling of 865800864 in words is "eight hundred sixty-five million, eight hundred thousand, eight hundred sixty-four".