18923028721 has 9 divisors (see below), whose sum is σ = 19070109849. Its totient is φ = 18777076500.

The previous prime is 18923028697. The next prime is 18923028727. The reversal of 18923028721 is 12782032981.

The square root of 18923028721 is 137561.

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

It is not a de Polignac number, because 18923028721 - 2³³ = 10333094129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18923028727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 20771256 + ... + 20772166.

Almost surely, 2^18923028721 is an apocalyptic number.

18923028721 is the 137561-st square number.

18923028721 is the 68781-st centered octagonal number.

It is an amenable number.

18923028721 is a deficient number, since it is larger than the sum of its proper divisors (147081128).

18923028721 is an frugal number, since it uses more digits than its factorization.

18923028721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2124 (or 1062 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 43.

The spelling of 18923028721 in words is "eighteen billion, nine hundred twenty-three million, twenty-eight thousand, seven hundred twenty-one".