638387631 has 72 divisors (see below), whose sum is σ = 1148550000. Its totient is φ = 339655680.

The previous prime is 638387623. The next prime is 638387653. The reversal of 638387631 is 136783836.

638387631 is a `hidden beast` number, since 6 + 3 + 8 + 3 + 8 + 7 + 631 = 666.

It is not a de Polignac number, because 638387631 - 2³ = 638387623 is a prime.

It is a super-2 number, since 2×638387631² = 815077534827584322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638387231) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 510495 + ... + 511743.

Almost surely, 2^638387631 is an apocalyptic number.

638387631 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

638387631 is a deficient number, since it is larger than the sum of its proper divisors (510162369).

638387631 is a wasteful number, since it uses less digits than its factorization.

638387631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1349 (or 1339 counting only the distinct ones).

The product of its digits is 435456, while the sum is 45.

The square root of 638387631 is about 25266.3339445991. Note that the first 3 decimals coincide. The cubic root of 638387631 is about 861.0495708124.

The spelling of 638387631 in words is "six hundred thirty-eight million, three hundred eighty-seven thousand, six hundred thirty-one".