18522789123721 has 9 divisors (see below), whose sum is σ = 18985764245799. Its totient is φ = 18070841626800.

The previous prime is 18522789123679. The next prime is 18522789123733. The reversal of 18522789123721 is 12732198722581.

The square root of 18522789123721 is 4303811.

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

It can be written as a sum of positive squares in only one way, i.e., 892531778121 + 17630257345600 = 944739^2 + 4198840^2 .

It is not a de Polignac number, because 18522789123721 - 2⁷ = 18522789123593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18522789183721) 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, 176403766 + ... + 176508736.

Almost surely, 2^{18522789123721} is an apocalyptic number.

18522789123721 is the 4303811-st square number.

18522789123721 is the 2151906-th centered octagonal number.

It is an amenable number.

18522789123721 is a deficient number, since it is larger than the sum of its proper divisors (462975122078).

18522789123721 is an frugal number, since it uses more digits than its factorization.

18522789123721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210024 (or 105012 counting only the distinct ones).

The product of its digits is 6773760, while the sum is 58.

The spelling of 18522789123721 in words is "eighteen trillion, five hundred twenty-two billion, seven hundred eighty-nine million, one hundred twenty-three thousand, seven hundred twenty-one".