109989 has 18 divisors (see below), whose sum is σ = 176358. Its totient is φ = 66000.

The previous prime is 109987. The next prime is 110017. The reversal of 109989 is 989901.

It can be written as a sum of positive squares in only one way, i.e., 108900 + 1089 = 330^2 + 33^2 .

It is not a de Polignac number, because 109989 - 2¹ = 109987 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (109987) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1039 + ... + 1139.

2¹⁰⁹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

109989 is a deficient number, since it is larger than the sum of its proper divisors (66369).

109989 is a wasteful number, since it uses less digits than its factorization.

109989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 115 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 109989 is about 331.6458954970. The cubic root of 109989 is about 47.9126013774.

Multiplying 109989 by its reverse (989901), we get a square (108878221089 = 329967²).

It can be divided in two parts, 10 and 9989, that added together give a palindrome (9999).

The spelling of 109989 in words is "one hundred nine thousand, nine hundred eighty-nine".