18039122721 has 36 divisors (see below), whose sum is σ = 26562075904. Its totient is φ = 11796911280.

The previous prime is 18039122719. The next prime is 18039122729. The reversal of 18039122721 is 12722193081.

18039122721 is a `hidden beast` number, since 180 + 391 + 22 + 72 + 1 = 666.

It is not a de Polignac number, because 18039122721 - 2¹ = 18039122719 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18039122729) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 10116396 + ... + 10118178.

Almost surely, 2^18039122721 is an apocalyptic number.

It is an amenable number.

18039122721 is a deficient number, since it is larger than the sum of its proper divisors (8522953183).

18039122721 is a wasteful number, since it uses less digits than its factorization.

18039122721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2154 (or 2080 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The spelling of 18039122721 in words is "eighteen billion, thirty-nine million, one hundred twenty-two thousand, seven hundred twenty-one".