Adding to 9900 its reverse (99), we get a palindrome (9999).
Subtracting from 9900 its reverse (99), we obtain a square (9801 = 992).
Multipling 9900 by its reverse (99), we get a square (980100 = 9902).
9900 divided by its reverse (99) gives a square (100 = 102).
9900 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a plaindrome in base 13 and base 16.
It is a nialpdrome in base 10.
It is a zygodrome in base 10.
29900 is an apocalyptic number.
9900 is a gapful number since it is divisible by the number (90) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 9900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16926).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
9900 is a wasteful number, since it uses less digits than its factorization.
9900 is an odious number, because the sum of its binary digits is odd.
The square root of 9900 is about 99.4987437107. The cubic root of 9900 is about 21.4722916902.
The spelling of 9900 in words is "nine thousand, nine hundred".