638636201657 has 2 divisors, whose sum is σ = 638636201658. Its totient is φ = 638636201656.

The previous prime is 638636201617. The next prime is 638636201663. The reversal of 638636201657 is 756102636836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 520632959401 + 118003242256 = 721549^2 + 343516^2 .

It is a cyclic number.

It is not a de Polignac number, because 638636201657 - 2¹² = 638636197561 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638636201599 and 638636201608.

It is not a weakly prime, because it can be changed into another prime (638636201617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319318100828 + 319318100829.

It is an arithmetic number, because the mean of its divisors is an integer number (319318100829).

Almost surely, 2^638636201657 is an apocalyptic number.

It is an amenable number.

638636201657 is a deficient number, since it is larger than the sum of its proper divisors (1).

638636201657 is an equidigital number, since it uses as much as digits as its factorization.

638636201657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6531840, while the sum is 53.

The spelling of 638636201657 in words is "six hundred thirty-eight billion, six hundred thirty-six million, two hundred one thousand, six hundred fifty-seven".