18685368370021 has 2 divisors, whose sum is σ = 18685368370022. Its totient is φ = 18685368370020.

The previous prime is 18685368369961. The next prime is 18685368370037. The reversal of 18685368370021 is 12007386358681.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11066360704996 + 7619007665025 = 3326614^2 + 2760255^2 .

It is a cyclic number.

It is not a de Polignac number, because 18685368370021 - 2⁷ = 18685368369893 is a prime.

It is a super-2 number, since 2×18685368370021² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18685368370091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9342684185010 + 9342684185011.

It is an arithmetic number, because the mean of its divisors is an integer number (9342684185011).

Almost surely, 2^{18685368370021} is an apocalyptic number.

It is an amenable number.

18685368370021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18685368370021 is an equidigital number, since it uses as much as digits as its factorization.

18685368370021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11612160, while the sum is 58.

The spelling of 18685368370021 in words is "eighteen trillion, six hundred eighty-five billion, three hundred sixty-eight million, three hundred seventy thousand, twenty-one".