18431939 has 4 divisors (see below), whose sum is σ = 18538656. Its totient is φ = 18325224.

The previous prime is 18431923. The next prime is 18431951. The reversal of 18431939 is 93913481.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 18431939 - 2⁴ = 18431923 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18431999) 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, 53099 + ... + 53444.

It is an arithmetic number, because the mean of its divisors is an integer number (4634664).

Almost surely, 2^18431939 is an apocalyptic number.

18431939 is a deficient number, since it is larger than the sum of its proper divisors (106717).

18431939 is a wasteful number, since it uses less digits than its factorization.

18431939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106716.

The product of its digits is 23328, while the sum is 38.

The square root of 18431939 is about 4293.2434126194. The cubic root of 18431939 is about 264.1538885085.

It can be divided in two parts, 184 and 31939, that added together give a palindrome (32123).

The spelling of 18431939 in words is "eighteen million, four hundred thirty-one thousand, nine hundred thirty-nine".