639401836 has 12 divisors (see below), whose sum is σ = 1119314728. Its totient is φ = 319597632.

The previous prime is 639401827. The next prime is 639401843. The reversal of 639401836 is 638104936.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10941 + ... + 37396.

Almost surely, 2^639401836 is an apocalyptic number.

It is an amenable number.

639401836 is a deficient number, since it is larger than the sum of its proper divisors (479912892).

639401836 is a wasteful number, since it uses less digits than its factorization.

639401836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51648 (or 51646 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 40.

The square root of 639401836 is about 25286.3962636039. The cubic root of 639401836 is about 861.5053120610.

The spelling of 639401836 in words is "six hundred thirty-nine million, four hundred one thousand, eight hundred thirty-six".