-20 is an even number.
-20 is a Harshad number, which means it is divisible by the sum of its digits (2 + 0 = 2, and -20 is divisible by 2).
In binary, -20 is represented as 1111111111111111111111111111111111111111111111111111111111101100.
In hex, -20 is represented as ffffffffffffffec.