638788913 has 16 divisors (see below), whose sum is σ = 776169216. Its totient is φ = 513839040.

The previous prime is 638788907. The next prime is 638788933. The reversal of 638788913 is 319887836.

It is a cyclic number.

It is not a de Polignac number, because 638788913 - 2²⁶ = 571680049 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (53).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638788933) 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, 28898 + ... + 45963.

It is an arithmetic number, because the mean of its divisors is an integer number (48510576).

Almost surely, 2^638788913 is an apocalyptic number.

It is an amenable number.

638788913 is a deficient number, since it is larger than the sum of its proper divisors (137380303).

638788913 is a wasteful number, since it uses less digits than its factorization.

638788913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74944.

The product of its digits is 1741824, while the sum is 53.

The square root of 638788913 is about 25274.2737383293. The cubic root of 638788913 is about 861.2299478045.

The spelling of 638788913 in words is "six hundred thirty-eight million, seven hundred eighty-eight thousand, nine hundred thirteen".