9966 has 16 divisors (see below), whose sum is σ = 21888. Its totient is φ = 3000.

The previous prime is 9949. The next prime is 9967. The reversal of 9966 is 6699.

9966 is an esthetic number in base 4, because in such base its adjacent digits differ by 1.

9966 is a strobogrammatic number because it is the same when read upside-down.

It is a plaindrome in base 8, base 14 and base 16.

It is a nialpdrome in base 10 and base 11.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9967) by changing a digit.

9966 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10 + ... + 141.

It is an arithmetic number, because the mean of its divisors is an integer number (1368).

2⁹⁹⁶⁶ is an apocalyptic number.

9966 is an abundant number, since it is smaller than the sum of its proper divisors (11922).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10944).

9966 is a wasteful number, since it uses less digits than its factorization.

9966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167.

The product of its digits is 2916, while the sum is 30.

The square root of 9966 is about 99.8298552538. The cubic root of 9966 is about 21.5199022489.

The spelling of 9966 in words is "nine thousand, nine hundred sixty-six".