18516900221 has 4 divisors (see below), whose sum is σ = 18599935872. Its totient is φ = 18433864572.

The previous prime is 18516900211. The next prime is 18516900289. The reversal of 18516900221 is 12200961581.

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 not a de Polignac number, because 18516900221 - 2¹⁰ = 18516899197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18516900211) 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, 41517491 + ... + 41517936.

It is an arithmetic number, because the mean of its divisors is an integer number (4649983968).

Almost surely, 2^18516900221 is an apocalyptic number.

It is an amenable number.

18516900221 is a deficient number, since it is larger than the sum of its proper divisors (83035651).

18516900221 is an equidigital number, since it uses as much as digits as its factorization.

18516900221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83035650.

The product of its (nonzero) digits is 8640, while the sum is 35.

The spelling of 18516900221 in words is "eighteen billion, five hundred sixteen million, nine hundred thousand, two hundred twenty-one".