638104681 has 2 divisors, whose sum is σ = 638104682. Its totient is φ = 638104680.

The previous prime is 638104667. The next prime is 638104693. The reversal of 638104681 is 186401836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 453008656 + 185096025 = 21284^2 + 13605^2 .

It is a cyclic number.

It is not a de Polignac number, because 638104681 - 2²⁵ = 604550249 is a prime.

It is a super-2 number, since 2×638104681² = 814355167828223522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 638104681.

It is not a weakly prime, because it can be changed into another prime (638104601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319052340 + 319052341.

It is an arithmetic number, because the mean of its divisors is an integer number (319052341).

Almost surely, 2^638104681 is an apocalyptic number.

It is an amenable number.

638104681 is a deficient number, since it is larger than the sum of its proper divisors (1).

638104681 is an equidigital number, since it uses as much as digits as its factorization.

638104681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 638104681 is about 25260.7339758765. The cubic root of 638104681 is about 860.9223388257.

The spelling of 638104681 in words is "six hundred thirty-eight million, one hundred four thousand, six hundred eighty-one".