18885981985817 has 2 divisors, whose sum is σ = 18885981985818. Its totient is φ = 18885981985816.

The previous prime is 18885981985789. The next prime is 18885981985841. The reversal of 18885981985817 is 71858918958881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14984207451136 + 3901774534681 = 3870944^2 + 1975291^2 .

It is a cyclic number.

It is not a de Polignac number, because 18885981985817 - 2²⁴ = 18885965208601 is a prime.

It is not a weakly prime, because it can be changed into another prime (18885981985877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9442990992908 + 9442990992909.

It is an arithmetic number, because the mean of its divisors is an integer number (9442990992909).

Almost surely, 2^{18885981985817} is an apocalyptic number.

It is an amenable number.

18885981985817 is a deficient number, since it is larger than the sum of its proper divisors (1).

18885981985817 is an equidigital number, since it uses as much as digits as its factorization.

18885981985817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3715891200, while the sum is 86.

The spelling of 18885981985817 in words is "eighteen trillion, eight hundred eighty-five billion, nine hundred eighty-one million, nine hundred eighty-five thousand, eight hundred seventeen".