9920 has 28 divisors (see below), whose sum is σ = 24384. Its totient is φ = 3840.

The previous prime is 9907. The next prime is 9923. The reversal of 9920 is 299.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a cake number, because a cake can be divided into 9920 parts by 39 planar cuts.

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 9892 and 9901.

It is not an unprimeable number, because it can be changed into a prime (9923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 305 + ... + 335.

2⁹⁹²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12192).

9920 is an abundant number, since it is smaller than the sum of its proper divisors (14464).

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

9920 is a wasteful number, since it uses less digits than its factorization.

9920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48 (or 38 counting only the distinct ones).

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 9920 is about 99.5991967839. The cubic root of 9920 is about 21.4867414198.

9920 divided by its sum of digits (20) gives a triangular number (496 = T₃₁).

It can be divided in two parts, 9 and 920, that added together give a palindrome (929).

The spelling of 9920 in words is "nine thousand, nine hundred twenty".