639669844 has 24 divisors (see below), whose sum is σ = 1222242336. Its totient is φ = 290508000.

The previous prime is 639669839. The next prime is 639669853. The reversal of 639669844 is 448966936.

It is a congruent number.

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, 51174 + ... + 62434.

It is an arithmetic number, because the mean of its divisors is an integer number (50926764).

Almost surely, 2^639669844 is an apocalyptic number.

It is an amenable number.

639669844 is a deficient number, since it is larger than the sum of its proper divisors (582572492).

639669844 is a wasteful number, since it uses less digits than its factorization.

639669844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12567 (or 12565 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 55.

The square root of 639669844 is about 25291.6951586880. The cubic root of 639669844 is about 861.6256631196.

The spelling of 639669844 in words is "six hundred thirty-nine million, six hundred sixty-nine thousand, eight hundred forty-four".