18787444909 has 2 divisors, whose sum is σ = 18787444910. Its totient is φ = 18787444908.

The previous prime is 18787444901. The next prime is 18787444919. The reversal of 18787444909 is 90944478781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17055054025 + 1732390884 = 130595^2 + 41622^2 .

It is a cyclic number.

It is not a de Polignac number, because 18787444909 - 2³ = 18787444901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18787444901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9393722454 + 9393722455.

It is an arithmetic number, because the mean of its divisors is an integer number (9393722455).

Almost surely, 2^18787444909 is an apocalyptic number.

It is an amenable number.

18787444909 is a deficient number, since it is larger than the sum of its proper divisors (1).

18787444909 is an equidigital number, since it uses as much as digits as its factorization.

18787444909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16257024, while the sum is 61.

The spelling of 18787444909 in words is "eighteen billion, seven hundred eighty-seven million, four hundred forty-four thousand, nine hundred nine".