18853721721 has 12 divisors (see below), whose sum is σ = 27243249072. Its totient is φ = 12564488376.

The previous prime is 18853721707. The next prime is 18853721737. The reversal of 18853721721 is 12712735881.

18853721721 is a `hidden beast` number, since 1 + 88 + 537 + 2 + 17 + 21 = 666.

It is not a de Polignac number, because 18853721721 - 2³⁰ = 17779979897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18853771721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 362571 + ... + 411296.

It is an arithmetic number, because the mean of its divisors is an integer number (2270270756).

Almost surely, 2^18853721721 is an apocalyptic number.

It is an amenable number.

18853721721 is a deficient number, since it is larger than the sum of its proper divisors (8389527351).

18853721721 is a wasteful number, since it uses less digits than its factorization.

18853721721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 776580 (or 776577 counting only the distinct ones).

The product of its digits is 188160, while the sum is 45.

The spelling of 18853721721 in words is "eighteen billion, eight hundred fifty-three million, seven hundred twenty-one thousand, seven hundred twenty-one".