638872401 has 4 divisors (see below), whose sum is σ = 851829872. Its totient is φ = 425914932.

The previous prime is 638872391. The next prime is 638872417. The reversal of 638872401 is 104278836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 638872401 - 2²⁵ = 605317969 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638872401.

It is not an unprimeable number, because it can be changed into a prime (638872501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106478731 + ... + 106478736.

It is an arithmetic number, because the mean of its divisors is an integer number (212957468).

Almost surely, 2^638872401 is an apocalyptic number.

It is an amenable number.

638872401 is a deficient number, since it is larger than the sum of its proper divisors (212957471).

638872401 is a wasteful number, since it uses less digits than its factorization.

638872401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212957470.

The product of its (nonzero) digits is 64512, while the sum is 39.

The square root of 638872401 is about 25275.9253243081. The cubic root of 638872401 is about 861.2674663192.

The spelling of 638872401 in words is "six hundred thirty-eight million, eight hundred seventy-two thousand, four hundred one".