638591117 has 4 divisors (see below), whose sum is σ = 650640060. Its totient is φ = 626542176.

The previous prime is 638591099. The next prime is 638591147. The reversal of 638591117 is 711195836.

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

It can be written as a sum of positive squares in 2 ways, for example, as 220552201 + 418038916 = 14851^2 + 20446^2 .

It is a cyclic number.

It is not a de Polignac number, because 638591117 - 2⁶ = 638591053 is a prime.

It is a super-2 number, since 2×638591117² = 815597229422615378, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638591147) 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, 6024392 + ... + 6024497.

It is an arithmetic number, because the mean of its divisors is an integer number (162660015).

Almost surely, 2^638591117 is an apocalyptic number.

It is an amenable number.

638591117 is a deficient number, since it is larger than the sum of its proper divisors (12048943).

638591117 is a wasteful number, since it uses less digits than its factorization.

638591117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12048942.

The product of its digits is 45360, while the sum is 41.

The square root of 638591117 is about 25270.3604445999. The cubic root of 638591117 is about 861.1410475848.

The spelling of 638591117 in words is "six hundred thirty-eight million, five hundred ninety-one thousand, one hundred seventeen".