638771117 has 2 divisors, whose sum is σ = 638771118. Its totient is φ = 638771116.

The previous prime is 638771069. The next prime is 638771123. The reversal of 638771117 is 711177836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 585349636 + 53421481 = 24194^2 + 7309^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638771117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638771137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319385558 + 319385559.

It is an arithmetic number, because the mean of its divisors is an integer number (319385559).

Almost surely, 2^638771117 is an apocalyptic number.

It is an amenable number.

638771117 is a deficient number, since it is larger than the sum of its proper divisors (1).

638771117 is an equidigital number, since it uses as much as digits as its factorization.

638771117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 49392, while the sum is 41.

The square root of 638771117 is about 25273.9216782833. The cubic root of 638771117 is about 861.2219500710.

The spelling of 638771117 in words is "six hundred thirty-eight million, seven hundred seventy-one thousand, one hundred seventeen".