18642491 has 6 divisors (see below), whose sum is σ = 21686220. Its totient is φ = 15979236.

The previous prime is 18642469. The next prime is 18642493. The reversal of 18642491 is 19424681.

It is a happy number.

It is not a de Polignac number, because 18642491 - 2⁶ = 18642427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18642493) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 190181 + ... + 190278.

It is an arithmetic number, because the mean of its divisors is an integer number (3614370).

Almost surely, 2^18642491 is an apocalyptic number.

18642491 is a deficient number, since it is larger than the sum of its proper divisors (3043729).

18642491 is an equidigital number, since it uses as much as digits as its factorization.

18642491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 380473 (or 380466 counting only the distinct ones).

The product of its digits is 13824, while the sum is 35.

The square root of 18642491 is about 4317.6951027139. The cubic root of 18642491 is about 265.1559115748.

The spelling of 18642491 in words is "eighteen million, six hundred forty-two thousand, four hundred ninety-one".