18431689 has 4 divisors (see below), whose sum is σ = 19515924. Its totient is φ = 17347456.

The previous prime is 18431681. The next prime is 18431711. The reversal of 18431689 is 98613481.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12306064 + 6125625 = 3508^2 + 2475^2 .

It is a cyclic number.

It is not a de Polignac number, because 18431689 - 2³ = 18431681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18431681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542092 + ... + 542125.

It is an arithmetic number, because the mean of its divisors is an integer number (4878981).

Almost surely, 2^18431689 is an apocalyptic number.

It is an amenable number.

18431689 is a deficient number, since it is larger than the sum of its proper divisors (1084235).

18431689 is a wasteful number, since it uses less digits than its factorization.

18431689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1084234.

The product of its digits is 41472, while the sum is 40.

The square root of 18431689 is about 4293.2142970041. The cubic root of 18431689 is about 264.1526942270.

The spelling of 18431689 in words is "eighteen million, four hundred thirty-one thousand, six hundred eighty-nine".