18520033681 has 2 divisors, whose sum is σ = 18520033682. Its totient is φ = 18520033680.

The previous prime is 18520033667. The next prime is 18520033691. The reversal of 18520033681 is 18633002581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15905245456 + 2614788225 = 126116^2 + 51135^2 .

It is a cyclic number.

It is not a de Polignac number, because 18520033681 - 2³³ = 9930099089 is a prime.

It is a super-2 number, since 2×18520033681² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18520033681.

It is not a weakly prime, because it can be changed into another prime (18520033601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9260016840 + 9260016841.

It is an arithmetic number, because the mean of its divisors is an integer number (9260016841).

Almost surely, 2^18520033681 is an apocalyptic number.

It is an amenable number.

18520033681 is a deficient number, since it is larger than the sum of its proper divisors (1).

18520033681 is an equidigital number, since it uses as much as digits as its factorization.

18520033681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 37.

The spelling of 18520033681 in words is "eighteen billion, five hundred twenty million, thirty-three thousand, six hundred eighty-one".