18998639 has 16 divisors (see below), whose sum is σ = 22083840. Its totient is φ = 16152960.

The previous prime is 18998611. The next prime is 18998641. The reversal of 18998639 is 93689981.

It is a cyclic number.

It is not a de Polignac number, because 18998639 - 2⁸ = 18998383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18998699) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52742 + ... + 53100.

It is an arithmetic number, because the mean of its divisors is an integer number (1380240).

Almost surely, 2^18998639 is an apocalyptic number.

18998639 is a deficient number, since it is larger than the sum of its proper divisors (3085201).

18998639 is a wasteful number, since it uses less digits than its factorization.

18998639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670.

The product of its digits is 839808, while the sum is 53.

The square root of 18998639 is about 4358.7428233379. The cubic root of 18998639 is about 266.8337933259.

The spelling of 18998639 in words is "eighteen million, nine hundred ninety-eight thousand, six hundred thirty-nine".