638620638953161 has 2 divisors, whose sum is σ = 638620638953162. Its totient is φ = 638620638953160.

The previous prime is 638620638953117. The next prime is 638620638953233. The reversal of 638620638953161 is 161359836026836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 552479148765625 + 86141490187536 = 23504875^2 + 9281244^2 .

It is a cyclic number.

It is not a de Polignac number, because 638620638953161 - 2⁹ = 638620638952649 is a prime.

It is not a weakly prime, because it can be changed into another prime (638620638956161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319310319476580 + 319310319476581.

It is an arithmetic number, because the mean of its divisors is an integer number (319310319476581).

Almost surely, 2^{638620638953161} is an apocalyptic number.

It is an amenable number.

638620638953161 is a deficient number, since it is larger than the sum of its proper divisors (1).

638620638953161 is an equidigital number, since it uses as much as digits as its factorization.

638620638953161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 201553920, while the sum is 67.

The spelling of 638620638953161 in words is "six hundred thirty-eight trillion, six hundred twenty billion, six hundred thirty-eight million, nine hundred fifty-three thousand, one hundred sixty-one".