639372857 has 16 divisors (see below), whose sum is σ = 680400000. Its totient is φ = 599122944.

The previous prime is 639372847. The next prime is 639372859. The reversal of 639372857 is 758273936.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 639372857 - 2¹⁸ = 639110713 is a prime.

It is a Duffinian number.

Its product of digits (1905120) is a multiple of the sum of its prime divisors (1120).

It is not an unprimeable number, because it can be changed into a prime (639372859) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1270868 + ... + 1271370.

It is an arithmetic number, because the mean of its divisors is an integer number (42525000).

Almost surely, 2^639372857 is an apocalyptic number.

It is an amenable number.

639372857 is a deficient number, since it is larger than the sum of its proper divisors (41027143).

639372857 is a wasteful number, since it uses less digits than its factorization.

639372857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1120.

The product of its digits is 1905120, while the sum is 50.

The square root of 639372857 is about 25285.8232414925. The cubic root of 639372857 is about 861.4922968029.

The spelling of 639372857 in words is "six hundred thirty-nine million, three hundred seventy-two thousand, eight hundred fifty-seven".