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: 9897 = 3 ⋅3299.
It is a cyclic number.
It is a D-number.
It is a plaindrome in base 15.
It is a congruent number.
27989 is an apocalyptic number.
It is an amenable number.
7989 is a wasteful number, since it uses less digits than its factorization.
7989 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 2666.
The square root of 7989 is about 89.3812060782. The cubic root of 7989 is about 19.9908291287.
The spelling of 7989 in words is "seven thousand, nine hundred eighty-nine".