18813139921 has 9 divisors (see below), whose sum is σ = 19858169961. Its totient is φ = 17820505764.

The previous prime is 18813139909. The next prime is 18813139951. The reversal of 18813139921 is 12993131881.

The square root of 18813139921 is 137161.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 18813139921 - 2²⁹ = 18276269009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18813139901) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2602450 + ... + 2609668.

It is an arithmetic number, because the mean of its divisors is an integer number (2206463329).

Almost surely, 2^18813139921 is an apocalyptic number.

18813139921 is the 137161-st square number.

18813139921 is the 68581-st centered octagonal number.

It is an amenable number.

18813139921 is a deficient number, since it is larger than the sum of its proper divisors (1045030040).

18813139921 is an frugal number, since it uses more digits than its factorization.

18813139921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14476 (or 7238 counting only the distinct ones).

The product of its digits is 93312, while the sum is 46.

The spelling of 18813139921 in words is "eighteen billion, eight hundred thirteen million, one hundred thirty-nine thousand, nine hundred twenty-one".