18885986331581 has 2 divisors, whose sum is σ = 18885986331582. Its totient is φ = 18885986331580.

The previous prime is 18885986331529. The next prime is 18885986331677. The reversal of 18885986331581 is 18513368958881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16225388205625 + 2660598125956 = 4028075^2 + 1631134^2 .

It is a cyclic number.

It is not a de Polignac number, because 18885986331581 - 2³⁴ = 18868806462397 is a prime.

It is a super-2 number, since 2×18885986331581² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 18885986331499 and 18885986331508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18885986331281) 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, 9442993165790 + 9442993165791.

It is an arithmetic number, because the mean of its divisors is an integer number (9442993165791).

Almost surely, 2^{18885986331581} is an apocalyptic number.

It is an amenable number.

18885986331581 is a deficient number, since it is larger than the sum of its proper divisors (1).

18885986331581 is an equidigital number, since it uses as much as digits as its factorization.

18885986331581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 398131200, while the sum is 74.

The spelling of 18885986331581 in words is "eighteen trillion, eight hundred eighty-five billion, nine hundred eighty-six million, three hundred thirty-one thousand, five hundred eighty-one".