18663587661 has 4 divisors (see below), whose sum is σ = 24884783552. Its totient is φ = 12442391772.

The previous prime is 18663587647. The next prime is 18663587773. The reversal of 18663587661 is 16678536681.

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 not a de Polignac number, because 18663587661 - 2⁵ = 18663587629 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18663583661) 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, 3110597941 + ... + 3110597946.

It is an arithmetic number, because the mean of its divisors is an integer number (6221195888).

Almost surely, 2^18663587661 is an apocalyptic number.

It is an amenable number.

18663587661 is a deficient number, since it is larger than the sum of its proper divisors (6221195891).

18663587661 is an equidigital number, since it uses as much as digits as its factorization.

18663587661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6221195890.

The product of its digits is 8709120, while the sum is 57.

The spelling of 18663587661 in words is "eighteen billion, six hundred sixty-three million, five hundred eighty-seven thousand, six hundred sixty-one".