639856872 has 96 divisors (see below), whose sum is σ = 1846990080. Its totient is φ = 199647360.

The previous prime is 639856843. The next prime is 639856883. The reversal of 639856872 is 278658936.

It is a happy number.

639856872 is a `hidden beast` number, since 6 + 3 + 9 + 8 + 568 + 72 = 666.

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 23 ways as a sum of consecutive naturals, for example, 73722 + ... + 81942.

It is an arithmetic number, because the mean of its divisors is an integer number (19239480).

Almost surely, 2^639856872 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 639856872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (923495040).

639856872 is an abundant number, since it is smaller than the sum of its proper divisors (1207133208).

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

639856872 is a wasteful number, since it uses less digits than its factorization.

639856872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8303 (or 8296 counting only the distinct ones).

The product of its digits is 4354560, while the sum is 54.

The square root of 639856872 is about 25295.3923076911. The cubic root of 639856872 is about 861.7096295715.

The spelling of 639856872 in words is "six hundred thirty-nine million, eight hundred fifty-six thousand, eight hundred seventy-two".