638632905 has 16 divisors (see below), whose sum is σ = 1024099200. Its totient is φ = 339842048.

The previous prime is 638632903. The next prime is 638632949. The reversal of 638632905 is 509236836.

It is a cyclic number.

It is not a de Polignac number, because 638632905 - 2¹ = 638632903 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638632901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40677 + ... + 54146.

It is an arithmetic number, because the mean of its divisors is an integer number (64006200).

Almost surely, 2^638632905 is an apocalyptic number.

It is an amenable number.

638632905 is a deficient number, since it is larger than the sum of its proper divisors (385466295).

638632905 is a wasteful number, since it uses less digits than its factorization.

638632905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95280.

The product of its (nonzero) digits is 233280, while the sum is 42.

The square root of 638632905 is about 25271.1872495140. The cubic root of 638632905 is about 861.1598309013.

The spelling of 638632905 in words is "six hundred thirty-eight million, six hundred thirty-two thousand, nine hundred five".