18561936665 has 32 divisors (see below), whose sum is σ = 23797547520. Its totient is φ = 13857951744.

The previous prime is 18561936661. The next prime is 18561936667. The reversal of 18561936665 is 56663916581.

It is a cyclic number.

It is not a de Polignac number, because 18561936665 - 2² = 18561936661 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18561936665.

It is not an unprimeable number, because it can be changed into a prime (18561936661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9201737 + ... + 9203753.

It is an arithmetic number, because the mean of its divisors is an integer number (743673360).

Almost surely, 2^18561936665 is an apocalyptic number.

It is an amenable number.

18561936665 is a deficient number, since it is larger than the sum of its proper divisors (5235610855).

18561936665 is a wasteful number, since it uses less digits than its factorization.

18561936665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3441.

The product of its digits is 6998400, while the sum is 56.

The spelling of 18561936665 in words is "eighteen billion, five hundred sixty-one million, nine hundred thirty-six thousand, six hundred sixty-five".