18381389 has 8 divisors (see below), whose sum is σ = 20478360. Its totient is φ = 16382016.

The previous prime is 18381373. The next prime is 18381397. The reversal of 18381389 is 98318381.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 20164 + 18361225 = 142^2 + 4285^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 18381389 - 2⁴ = 18381373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18381329) 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, 24002 + ... + 24755.

It is an arithmetic number, because the mean of its divisors is an integer number (2559795).

Almost surely, 2^18381389 is an apocalyptic number.

It is an amenable number.

18381389 is a deficient number, since it is larger than the sum of its proper divisors (2096971).

18381389 is a wasteful number, since it uses less digits than its factorization.

18381389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48799.

The product of its digits is 41472, while the sum is 41.

The square root of 18381389 is about 4287.3522131964. The cubic root of 18381389 is about 263.9121847890.

The spelling of 18381389 in words is "eighteen million, three hundred eighty-one thousand, three hundred eighty-nine".