18399889 has 4 divisors (see below), whose sum is σ = 18791424. Its totient is φ = 18008356.

The previous prime is 18399883. The next prime is 18399907. The reversal of 18399889 is 98899381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18399889 - 2⁹ = 18399377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18399883) 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, 195697 + ... + 195790.

It is an arithmetic number, because the mean of its divisors is an integer number (4697856).

Almost surely, 2^18399889 is an apocalyptic number.

It is an amenable number.

18399889 is a deficient number, since it is larger than the sum of its proper divisors (391535).

18399889 is an equidigital number, since it uses as much as digits as its factorization.

18399889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391534.

The product of its digits is 1119744, while the sum is 55.

The square root of 18399889 is about 4289.5091793817. The cubic root of 18399889 is about 264.0006934861. Note that the first 3 decimals are identical.

The spelling of 18399889 in words is "eighteen million, three hundred ninety-nine thousand, eight hundred eighty-nine".