638835923 has 4 divisors (see below), whose sum is σ = 696911928. Its totient is φ = 580759920.

The previous prime is 638835887. The next prime is 638835937. The reversal of 638835923 is 329538836.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638835923 - 2⁸ = 638835667 is a prime.

It is a super-2 number, since 2×638835923² = 816222673030523858, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638835943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29037986 + ... + 29038007.

It is an arithmetic number, because the mean of its divisors is an integer number (174227982).

Almost surely, 2^638835923 is an apocalyptic number.

638835923 is a deficient number, since it is larger than the sum of its proper divisors (58076005).

638835923 is a wasteful number, since it uses less digits than its factorization.

638835923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58076004.

The product of its digits is 933120, while the sum is 47.

The square root of 638835923 is about 25275.2037182690. The cubic root of 638835923 is about 861.2510739417.

The spelling of 638835923 in words is "six hundred thirty-eight million, eight hundred thirty-five thousand, nine hundred twenty-three".