18121994244 has 36 divisors (see below), whose sum is σ = 47504983344. Its totient is φ = 6040664424.

The previous prime is 18121994243. The next prime is 18121994263. The reversal of 18121994244 is 44249912181.

18121994244 is a `hidden beast` number, since 1 + 8 + 1 + 219 + 9 + 424 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a self number, because there is not a number n which added to its sum of digits gives 18121994244.

It is not an unprimeable number, because it can be changed into a prime (18121994243) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9321042 + ... + 9322985.

Almost surely, 2^18121994244 is an apocalyptic number.

It is an amenable number.

18121994244 is an abundant number, since it is smaller than the sum of its proper divisors (29382989100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18121994244 is a wasteful number, since it uses less digits than its factorization.

18121994244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18644046 (or 18644032 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The spelling of 18121994244 in words is "eighteen billion, one hundred twenty-one million, nine hundred ninety-four thousand, two hundred forty-four".