18166244891 has 2 divisors, whose sum is σ = 18166244892. Its totient is φ = 18166244890.

The previous prime is 18166244881. The next prime is 18166244969. The reversal of 18166244891 is 19844266181.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18166244891 - 2¹⁰ = 18166243867 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (18166244821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9083122445 + 9083122446.

It is an arithmetic number, because the mean of its divisors is an integer number (9083122446).

Almost surely, 2^18166244891 is an apocalyptic number.

18166244891 is a deficient number, since it is larger than the sum of its proper divisors (1).

18166244891 is an equidigital number, since it uses as much as digits as its factorization.

18166244891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 663552, while the sum is 50.

The spelling of 18166244891 in words is "eighteen billion, one hundred sixty-six million, two hundred forty-four thousand, eight hundred ninety-one".