18431139 has 4 divisors (see below), whose sum is σ = 24574856. Its totient is φ = 12287424.

The previous prime is 18431131. The next prime is 18431167. The reversal of 18431139 is 93113481.

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

It is not a de Polignac number, because 18431139 - 2³ = 18431131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18431131) 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, 3071854 + ... + 3071859.

It is an arithmetic number, because the mean of its divisors is an integer number (6143714).

Almost surely, 2^18431139 is an apocalyptic number.

18431139 is a deficient number, since it is larger than the sum of its proper divisors (6143717).

18431139 is an equidigital number, since it uses as much as digits as its factorization.

18431139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6143716.

The product of its digits is 2592, while the sum is 30.

The square root of 18431139 is about 4293.1502419552. The cubic root of 18431139 is about 264.1500667697.

The spelling of 18431139 in words is "eighteen million, four hundred thirty-one thousand, one hundred thirty-nine".