639640044 has 24 divisors (see below), whose sum is σ = 1658326320. Its totient is φ = 213213312.

The previous prime is 639640033. The next prime is 639640109. The reversal of 639640044 is 440046936.

639640044 is a `hidden beast` number, since 6 + 3 + 9 + 640 + 0 + 4 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 639639990 and 639640008.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2961189 + ... + 2961404.

It is an arithmetic number, because the mean of its divisors is an integer number (69096930).

Almost surely, 2^639640044 is an apocalyptic number.

It is an amenable number.

639640044 is an abundant number, since it is smaller than the sum of its proper divisors (1018686276).

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

639640044 is a wasteful number, since it uses less digits than its factorization.

639640044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5922606 (or 5922598 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The square root of 639640044 is about 25291.1060256368. The cubic root of 639640044 is about 861.6122828612.

The spelling of 639640044 in words is "six hundred thirty-nine million, six hundred forty thousand, forty-four".