18398018 has 4 divisors (see below), whose sum is σ = 27597030. Its totient is φ = 9199008.

The previous prime is 18398011. The next prime is 18398021. The reversal of 18398018 is 81089381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81089381 = 97 ⋅835973.

It can be written as a sum of positive squares in only one way, i.e., 14799409 + 3598609 = 3847^2 + 1897^2 .

It is not an unprimeable number, because it can be changed into a prime (18398011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4599503 + ... + 4599506.

Almost surely, 2^18398018 is an apocalyptic number.

18398018 is a deficient number, since it is larger than the sum of its proper divisors (9199012).

18398018 is an equidigital number, since it uses as much as digits as its factorization.

18398018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9199011.

The product of its (nonzero) digits is 13824, while the sum is 38.

The square root of 18398018 is about 4289.2910836174. The cubic root of 18398018 is about 263.9917448444.

The spelling of 18398018 in words is "eighteen million, three hundred ninety-eight thousand, eighteen".