18181566643 has 2 divisors, whose sum is σ = 18181566644. Its totient is φ = 18181566642.

The previous prime is 18181566629. The next prime is 18181566703. The reversal of 18181566643 is 34666518181.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18181566643 - 2³³ = 9591632051 is a prime.

It is not a weakly prime, because it can be changed into another prime (18181566043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9090783321 + 9090783322.

It is an arithmetic number, because the mean of its divisors is an integer number (9090783322).

Almost surely, 2^18181566643 is an apocalyptic number.

18181566643 is a deficient number, since it is larger than the sum of its proper divisors (1).

18181566643 is an equidigital number, since it uses as much as digits as its factorization.

18181566643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 829440, while the sum is 49.

The spelling of 18181566643 in words is "eighteen billion, one hundred eighty-one million, five hundred sixty-six thousand, six hundred forty-three".