19920 has 40 divisors (see below), whose sum is σ = 62496. Its totient is φ = 5248.

The previous prime is 19919. The next prime is 19927. The reversal of 19920 is 2991.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19927) by changing a digit.

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, 199 + ... + 281.

2¹⁹⁹²⁰ is an apocalyptic number.

19920 is a gapful number since it is divisible by the number (10) 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 19920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31248).

19920 is an abundant number, since it is smaller than the sum of its proper divisors (42576).

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

19920 is a wasteful number, since it uses less digits than its factorization.

19920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 93 counting only the distinct ones).

The product of its (nonzero) digits is 162, while the sum is 21.

The square root of 19920 is about 141.1382301150. The cubic root of 19920 is about 27.1079355672.

It can be divided in two parts, 19 and 920, that added together give a palindrome (939).

The spelling of 19920 in words is "nineteen thousand, nine hundred twenty".