639955936 has 24 divisors (see below), whose sum is σ = 1265335344. Its totient is φ = 318600960.

The previous prime is 639955919. The next prime is 639955961. The reversal of 639955936 is 639559936.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35460 + ... + 50371.

It is an arithmetic number, because the mean of its divisors is an integer number (52722306).

Almost surely, 2^639955936 is an apocalyptic number.

It is an amenable number.

639955936 is a deficient number, since it is larger than the sum of its proper divisors (625379408).

639955936 is a wasteful number, since it uses less digits than its factorization.

639955936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86074 (or 86066 counting only the distinct ones).

The product of its digits is 5904900, while the sum is 55.

The square root of 639955936 is about 25297.3503750887. The cubic root of 639955936 is about 861.7540978484.

The spelling of 639955936 in words is "six hundred thirty-nine million, nine hundred fifty-five thousand, nine hundred thirty-six".