638881944 has 32 divisors (see below), whose sum is σ = 1597873920. Its totient is φ = 212871456.

The previous prime is 638881939. The next prime is 638881987. The reversal of 638881944 is 449188836.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79269 + ... + 86955.

It is an arithmetic number, because the mean of its divisors is an integer number (49933560).

Almost surely, 2^638881944 is an apocalyptic number.

It is an amenable number.

638881944 is an abundant number, since it is smaller than the sum of its proper divisors (958991976).

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

638881944 is a wasteful number, since it uses less digits than its factorization.

638881944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11159 (or 11155 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 51.

The square root of 638881944 is about 25276.1141000748. The cubic root of 638881944 is about 861.2717546218.

The spelling of 638881944 in words is "six hundred thirty-eight million, eight hundred eighty-one thousand, nine hundred forty-four".