18993978236 has 12 divisors (see below), whose sum is σ = 33462546600. Its totient is φ = 9433250640.

The previous prime is 18993978233. The next prime is 18993978253. The reversal of 18993978236 is 63287939981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18993978233) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15933950 + ... + 15935141.

It is an arithmetic number, because the mean of its divisors is an integer number (2788545550).

Almost surely, 2^18993978236 is an apocalyptic number.

It is an amenable number.

18993978236 is a deficient number, since it is larger than the sum of its proper divisors (14468568364).

18993978236 is a wasteful number, since it uses less digits than its factorization.

18993978236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31869244 (or 31869242 counting only the distinct ones).

The product of its digits is 35271936, while the sum is 65.

The spelling of 18993978236 in words is "eighteen billion, nine hundred ninety-three million, nine hundred seventy-eight thousand, two hundred thirty-six".