18561198761 has 4 divisors (see below), whose sum is σ = 21212798592. Its totient is φ = 15909598932.

The previous prime is 18561198737. The next prime is 18561198763. The reversal of 18561198761 is 16789116581.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18561198761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18561198763) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1325799905 + ... + 1325799918.

It is an arithmetic number, because the mean of its divisors is an integer number (5303199648).

Almost surely, 2^18561198761 is an apocalyptic number.

It is an amenable number.

18561198761 is a deficient number, since it is larger than the sum of its proper divisors (2651599831).

18561198761 is an equidigital number, since it uses as much as digits as its factorization.

18561198761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2651599830.

The product of its digits is 725760, while the sum is 53.

The spelling of 18561198761 in words is "eighteen billion, five hundred sixty-one million, one hundred ninety-eight thousand, seven hundred sixty-one".