18139999 has 4 divisors (see below), whose sum is σ = 18582480. Its totient is φ = 17697520.

The previous prime is 18139987. The next prime is 18140009. The reversal of 18139999 is 99993181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99993181 = 19 ⋅5262799.

It is a cyclic number.

It is not a de Polignac number, because 18139999 - 2⁵ = 18139967 is a prime.

It is a Duffinian number.

18139999 is a modest number, since divided by 9999 gives 1813 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18139909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 221179 + ... + 221260.

It is an arithmetic number, because the mean of its divisors is an integer number (4645620).

Almost surely, 2^18139999 is an apocalyptic number.

18139999 is a deficient number, since it is larger than the sum of its proper divisors (442481).

18139999 is an equidigital number, since it uses as much as digits as its factorization.

18139999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442480.

The product of its digits is 157464, while the sum is 49.

The square root of 18139999 is about 4259.1077704139. The cubic root of 18139999 is about 262.7518320967.

The spelling of 18139999 in words is "eighteen million, one hundred thirty-nine thousand, nine hundred ninety-nine".