638620638923161 has 2 divisors, whose sum is σ = 638620638923162. Its totient is φ = 638620638923160.

The previous prime is 638620638923153. The next prime is 638620638923257. The reversal of 638620638923161 is 161329836026836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 413531950185225 + 225088688737936 = 20335485^2 + 15002956^2 .

It is a cyclic number.

It is not a de Polignac number, because 638620638923161 - 2³ = 638620638923153 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638620638923093 and 638620638923102.

It is not a weakly prime, because it can be changed into another prime (638620638953161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319310319461580 + 319310319461581.

It is an arithmetic number, because the mean of its divisors is an integer number (319310319461581).

Almost surely, 2^{638620638923161} is an apocalyptic number.

It is an amenable number.

638620638923161 is a deficient number, since it is larger than the sum of its proper divisors (1).

638620638923161 is an equidigital number, since it uses as much as digits as its factorization.

638620638923161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80621568, while the sum is 64.

The spelling of 638620638923161 in words is "six hundred thirty-eight trillion, six hundred twenty billion, six hundred thirty-eight million, nine hundred twenty-three thousand, one hundred sixty-one".