638968908 has 12 divisors (see below), whose sum is σ = 1490927480. Its totient is φ = 212989632.

The previous prime is 638968903. The next prime is 638968921. The reversal of 638968908 is 809869836.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (638968903) by changing a digit.

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, 26623693 + ... + 26623716.

Almost surely, 2^638968908 is an apocalyptic number.

It is an amenable number.

638968908 is an abundant number, since it is smaller than the sum of its proper divisors (851958572).

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

638968908 is a wasteful number, since it uses less digits than its factorization.

638968908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53247416 (or 53247414 counting only the distinct ones).

The product of its (nonzero) digits is 4478976, while the sum is 57.

The square root of 638968908 is about 25277.8343217927. The cubic root of 638968908 is about 861.3108313450.

The spelling of 638968908 in words is "six hundred thirty-eight million, nine hundred sixty-eight thousand, nine hundred eight".