638008665 has 24 divisors (see below), whose sum is σ = 1187478720. Its totient is φ = 291660768.

The previous prime is 638008621. The next prime is 638008669. The reversal of 638008665 is 566800836.

638008665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 638008665 - 2⁹ = 638008153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638008669) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 433285 + ... + 434754.

It is an arithmetic number, because the mean of its divisors is an integer number (49478280).

Almost surely, 2^638008665 is an apocalyptic number.

It is an amenable number.

638008665 is a deficient number, since it is larger than the sum of its proper divisors (549470055).

638008665 is a wasteful number, since it uses less digits than its factorization.

638008665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868061 (or 868054 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The square root of 638008665 is about 25258.8334053653. The cubic root of 638008665 is about 860.8791554901.

The spelling of 638008665 in words is "six hundred thirty-eight million, eight thousand, six hundred sixty-five".