18991389388 has 6 divisors (see below), whose sum is σ = 33234931436. Its totient is φ = 9495694692.

The previous prime is 18991389377. The next prime is 18991389419. The reversal of 18991389388 is 88398319981.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2373923670 + ... + 2373923677.

Almost surely, 2^18991389388 is an apocalyptic number.

It is an amenable number.

18991389388 is a deficient number, since it is larger than the sum of its proper divisors (14243542048).

18991389388 is a wasteful number, since it uses less digits than its factorization.

18991389388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4747847351 (or 4747847349 counting only the distinct ones).

The product of its digits is 26873856, while the sum is 67.

The spelling of 18991389388 in words is "eighteen billion, nine hundred ninety-one million, three hundred eighty-nine thousand, three hundred eighty-eight".