19720 has 32 divisors (see below), whose sum is σ = 48600. Its totient is φ = 7168.

The previous prime is 19717. The next prime is 19727. The reversal of 19720 is 2791.

19720 = 29² + 30² + ... + 43².

It can be written as a sum of positive squares in 4 ways, for example, as 17956 + 1764 = 134^2 + 42^2 .

19720 is an undulating number in base 12 and base 13.

It is not an unprimeable number, because it can be changed into a prime (19727) 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 7 ways as a sum of consecutive naturals, for example, 666 + ... + 694.

2¹⁹⁷²⁰ is an apocalyptic number.

19720 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 19720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24300).

19720 is an abundant number, since it is smaller than the sum of its proper divisors (28880).

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

19720 is a wasteful number, since it uses less digits than its factorization.

19720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 19.

The square root of 19720 is about 140.4279174523. The cubic root of 19720 is about 27.0169075629.

Subtracting from 19720 its sum of digits (19), we obtain a triangular number (19701 = T₁₉₈).

The spelling of 19720 in words is "nineteen thousand, seven hundred twenty".