18989 has 4 divisors (see below), whose sum is σ = 20124. Its totient is φ = 17856.

The previous prime is 18979. The next prime is 19001. The reversal of 18989 is 98981.

18989 = 5² + 6² + ... + 38².

It is a happy number.

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 6889 + 12100 = 83^2 + 110^2 .

It is a cyclic number.

It is not a de Polignac number, because 18989 - 2⁴ = 18973 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542 + ... + 575.

It is an arithmetic number, because the mean of its divisors is an integer number (5031).

2¹⁸⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

18989 is a deficient number, since it is larger than the sum of its proper divisors (1135).

18989 is a wasteful number, since it uses less digits than its factorization.

18989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1134.

The product of its digits is 5184, while the sum is 35.

The square root of 18989 is about 137.8005805503. The cubic root of 18989 is about 26.6788659461.

The spelling of 18989 in words is "eighteen thousand, nine hundred eighty-nine".