18931389 has 8 divisors (see below), whose sum is σ = 25669920. Its totient is φ = 12406896.

The previous prime is 18931379. The next prime is 18931399. The reversal of 18931389 is 98313981.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18931379) and next prime (18931399).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18931389 - 2⁴ = 18931373 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18931389.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18931349) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53302 + ... + 53655.

It is an arithmetic number, because the mean of its divisors is an integer number (3208740).

Almost surely, 2^18931389 is an apocalyptic number.

It is an amenable number.

18931389 is a deficient number, since it is larger than the sum of its proper divisors (6738531).

18931389 is a wasteful number, since it uses less digits than its factorization.

18931389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107019.

The product of its digits is 46656, while the sum is 42.

The square root of 18931389 is about 4351.0216041753. The cubic root of 18931389 is about 266.5185814959.

The spelling of 18931389 in words is "eighteen million, nine hundred thirty-one thousand, three hundred eighty-nine".