9906 has 16 divisors (see below), whose sum is σ = 21504. Its totient is φ = 3024.

The previous prime is 9901. The next prime is 9907. The reversal of 9906 is 6099.

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.

It is not an unprimeable number, because it can be changed into a prime (9901) by changing a digit.

9906 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15 + ... + 141.

It is an arithmetic number, because the mean of its divisors is an integer number (1344).

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).

9906 is an abundant number, since it is smaller than the sum of its proper divisors (11598).

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 product of its (nonzero) digits is 486, while the sum is 24.

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".