Subtracting from 9990 its product of nonzero digits (729), we obtain a cube (9261 = 213).
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a nialpdrome in base 10.
It is a congruent number.
It is an unprimeable number.
29990 is an apocalyptic number.
9990 is a gapful number since it is divisible by the number (90) formed by its first and last digit.
It is a practical number, because each smaller number is the sum of distinct divisors of 9990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13680).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
9990 is a wasteful number, since it uses less digits than its factorization.
9990 is an evil number, because the sum of its binary digits is even.
The square root of 9990 is about 99.9499874937. The cubic root of 9990 is about 21.5371630562.
The spelling of 9990 in words is "nine thousand, nine hundred ninety".