Today is 20 day of the year.
20 = 2^2 x 5
20 is a tetrahedral number or, equivalently, the sum of the first four triangular numbers.
20 is the fifth oblong, promic, pronic or heteromecic number.
20 is the number of possible paths from one corner of a 3-by-3 grid to the opposite corner.
20 is a member of two primitive, Pythagorean triples (20, 21, 29) and (20, 99, 101).