18387389 has 4 divisors (see below), whose sum is σ = 18480924. Its totient is φ = 18293856.

The previous prime is 18387377. The next prime is 18387403. The reversal of 18387389 is 98378381.

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 13935289 + 4452100 = 3733^2 + 2110^2 .

It is a cyclic number.

It is not a de Polignac number, because 18387389 - 2²⁰ = 17338813 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18387349) 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, 46472 + ... + 46865.

It is an arithmetic number, because the mean of its divisors is an integer number (4620231).

Almost surely, 2^18387389 is an apocalyptic number.

It is an amenable number.

18387389 is a deficient number, since it is larger than the sum of its proper divisors (93535).

18387389 is an equidigital number, since it uses as much as digits as its factorization.

18387389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93534.

The product of its digits is 290304, while the sum is 47.

The square root of 18387389 is about 4288.0518886786. The cubic root of 18387389 is about 263.9408968167.

The spelling of 18387389 in words is "eighteen million, three hundred eighty-seven thousand, three hundred eighty-nine".