638736844 has 12 divisors (see below), whose sum is σ = 1118084968. Its totient is φ = 319284000.

The previous prime is 638736829. The next prime is 638736863. The reversal of 638736844 is 448637836.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2202 + ... + 35809.

Almost surely, 2^638736844 is an apocalyptic number.

It is an amenable number.

638736844 is a deficient number, since it is larger than the sum of its proper divisors (479348124).

638736844 is a wasteful number, since it uses less digits than its factorization.

638736844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42216 (or 42214 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 49.

The square root of 638736844 is about 25273.2436382828. The cubic root of 638736844 is about 861.2065469597.

The spelling of 638736844 in words is "six hundred thirty-eight million, seven hundred thirty-six thousand, eight hundred forty-four".