9989 has 4 divisors (see below), whose sum is σ = 11424. Its totient is φ = 8556.

The previous prime is 9973. The next prime is 10007. The reversal of 9989 is 9899.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9899 = 19 ⋅521.

It is a cyclic number.

It is not a de Polignac number, because 9989 - 2⁴ = 9973 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 (9929) 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, 707 + ... + 720.

It is an arithmetic number, because the mean of its divisors is an integer number (2856).

2⁹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

9989 is a deficient number, since it is larger than the sum of its proper divisors (1435).

9989 is a wasteful number, since it uses less digits than its factorization.

9989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1434.

The product of its digits is 5832, while the sum is 35.

The square root of 9989 is about 99.9449848667. The cubic root of 9989 is about 21.5364444082.

The spelling of 9989 in words is "nine thousand, nine hundred eighty-nine".