100989 has 18 divisors (see below), whose sum is σ = 170430. Its totient is φ = 57456.

The previous prime is 100987. The next prime is 100999. The reversal of 100989 is 989001.

It can be written as a sum of positive squares in only one way, i.e., 99225 + 1764 = 315^2 + 42^2 .

It is not a de Polignac number, because 100989 - 2¹ = 100987 is a prime.

It is an Ulam 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 (100981) 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, 327 + ... + 555.

2¹⁰⁰⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

100989 is a deficient number, since it is larger than the sum of its proper divisors (69441).

100989 is a wasteful number, since it uses less digits than its factorization.

100989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 100989 is about 317.7876649589. The cubic root of 100989 is about 46.5684043531.

It can be divided in two parts, 100 and 989, that added together give a square (1089 = 33²).

The spelling of 100989 in words is "one hundred thousand, nine hundred eighty-nine".