638949836 has 36 divisors (see below), whose sum is σ = 1291254384. Its totient is φ = 271003200.

The previous prime is 638949833. The next prime is 638949851.

638949836 is nontrivially palindromic in base 10.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (638949833) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 284510 + ... + 286746.

Almost surely, 2^638949836 is an apocalyptic number.

It is an amenable number.

638949836 is an abundant number, since it is smaller than the sum of its proper divisors (652304548).

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

638949836 is a wasteful number, since it uses less digits than its factorization.

638949836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2450 (or 2347 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 56.

The square root of 638949836 is about 25277.4570714698. The cubic root of 638949836 is about 861.3022617660.

The spelling of 638949836 in words is "six hundred thirty-eight million, nine hundred forty-nine thousand, eight hundred thirty-six".