638909836 has 6 divisors (see below), whose sum is σ = 1118092220. Its totient is φ = 319454916.

The previous prime is 638909813. The next prime is 638909837.

638909836 is nontrivially palindromic in base 10.

638909836 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 (638909837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79863726 + ... + 79863733.

Almost surely, 2^638909836 is an apocalyptic number.

It is an amenable number.

638909836 is a deficient number, since it is larger than the sum of its proper divisors (479182384).

638909836 is a wasteful number, since it uses less digits than its factorization.

638909836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159727463 (or 159727461 counting only the distinct ones).

The product of its (nonzero) digits is 1679616, while the sum is 52.

The square root of 638909836 is about 25276.6658402567. The cubic root of 638909836 is about 861.2842881018.

The spelling of 638909836 in words is "six hundred thirty-eight million, nine hundred nine thousand, eight hundred thirty-six".