9906 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a Curzon number.
9906 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
29906 is an apocalyptic number.
It is a practical number, because each smaller number is the sum of distinct divisors of 9906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10752).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
9906 is a wasteful number, since it uses less digits than its factorization.
9906 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 145.
The square root of 9906 is about 99.5288902781. The cubic root of 9906 is about 21.4766286509.
The spelling of 9906 in words is "nine thousand, nine hundred six".