-90 is an even number.
-90 is a Harshad number, which means it is divisible by the sum of its digits (9 + 0 = 9, and -90 is divisible by 9).
In binary, -90 is represented as 1111111111111111111111111111111111111111111111111111111110100110.
In hex, -90 is represented as ffffffffffffffa6.