18191998 has 16 divisors (see below), whose sum is σ = 29917440. Its totient is φ = 8227800.

The previous prime is 18191993. The next prime is 18192029. The reversal of 18191998 is 89919181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18191993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2683 + ... + 6601.

It is an arithmetic number, because the mean of its divisors is an integer number (1869840).

Almost surely, 2^18191998 is an apocalyptic number.

18191998 is a deficient number, since it is larger than the sum of its proper divisors (11725442).

18191998 is a wasteful number, since it uses less digits than its factorization.

18191998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4143.

The product of its digits is 46656, while the sum is 46.

The square root of 18191998 is about 4265.2078495661. The cubic root of 18191998 is about 263.0026553053.

The spelling of 18191998 in words is "eighteen million, one hundred ninety-one thousand, nine hundred ninety-eight".