18215998 has 4 divisors (see below), whose sum is σ = 27324000. Its totient is φ = 9107998.

The previous prime is 18215983. The next prime is 18216017. The reversal of 18215998 is 89951281.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4553998 + ... + 4554001.

It is an arithmetic number, because the mean of its divisors is an integer number (6831000).

Almost surely, 2^18215998 is an apocalyptic number.

18215998 is a deficient number, since it is larger than the sum of its proper divisors (9108002).

18215998 is an equidigital number, since it uses as much as digits as its factorization.

18215998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9108001.

The product of its digits is 51840, while the sum is 43.

The square root of 18215998 is about 4268.0203842062. The cubic root of 18215998 is about 263.1182608957.

The spelling of 18215998 in words is "eighteen million, two hundred fifteen thousand, nine hundred ninety-eight".