639572864 has 64 divisors (see below), whose sum is σ = 1459628160. Its totient is φ = 273452544.

The previous prime is 639572839. The next prime is 639572887. The reversal of 639572864 is 468275936.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 704699 + ... + 705605.

It is an arithmetic number, because the mean of its divisors is an integer number (22806690).

Almost surely, 2^639572864 is an apocalyptic number.

639572864 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639572864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (729814080).

639572864 is an abundant number, since it is smaller than the sum of its proper divisors (820055296).

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

639572864 is an equidigital number, since it uses as much as digits as its factorization.

639572864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1715 (or 1703 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 50.

The square root of 639572864 is about 25289.7778558848. Note that the first 3 decimals coincide. The cubic root of 639572864 is about 861.5821173849.

The spelling of 639572864 in words is "six hundred thirty-nine million, five hundred seventy-two thousand, eight hundred sixty-four".