638636201617 has 2 divisors, whose sum is σ = 638636201618. Its totient is φ = 638636201616.

The previous prime is 638636201603. The next prime is 638636201657. The reversal of 638636201617 is 716102636836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 328614416001 + 310021785616 = 573249^2 + 556796^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638636201617 is a prime.

It is not a weakly prime, because it can be changed into another prime (638636201657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319318100808 + 319318100809.

It is an arithmetic number, because the mean of its divisors is an integer number (319318100809).

Almost surely, 2^638636201617 is an apocalyptic number.

It is an amenable number.

638636201617 is a deficient number, since it is larger than the sum of its proper divisors (1).

638636201617 is an equidigital number, since it uses as much as digits as its factorization.

638636201617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1306368, while the sum is 49.

The spelling of 638636201617 in words is "six hundred thirty-eight billion, six hundred thirty-six million, two hundred one thousand, six hundred seventeen".