639899031 has 32 divisors (see below), whose sum is σ = 913397760. Its totient is φ = 398298912.

The previous prime is 639899017. The next prime is 639899033. The reversal of 639899031 is 130998936.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-639899031 is a prime.

It is a super-2 number, since 2×639899031² = 818941539749477922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639899033) 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 31 ways as a sum of consecutive naturals, for example, 1715361 + ... + 1715733.

It is an arithmetic number, because the mean of its divisors is an integer number (28543680).

Almost surely, 2^639899031 is an apocalyptic number.

639899031 is a deficient number, since it is larger than the sum of its proper divisors (273498729).

639899031 is an equidigital number, since it uses as much as digits as its factorization.

639899031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492 (or 446 counting only the distinct ones).

The product of its (nonzero) digits is 314928, while the sum is 48.

The square root of 639899031 is about 25296.2256275516. The cubic root of 639899031 is about 861.7285546468.

The spelling of 639899031 in words is "six hundred thirty-nine million, eight hundred ninety-nine thousand, thirty-one".