Unique Numbers, Special Meanings

Do you know that number 0 to 9999 has its own special meaning? I came across this page, What’s Special About This Number? and found out this interesting stuff.

Here are some unique numbers:

0 is the additive identity.
7 is the smallest number of faces of a regular polygon that is not constructible by straightedge and compass.
10 is the base of our number system.
36 is the smallest number (besides 1) which is both square and triangular.
69 has the property that n2 and n3 together contain each digit once.
88 is the only number known whose square has no isolated digits.
101 is the number of partitions of 13.
456 is the number of tournaments with 7 vertices.
2020 is a curious number.
9999 is a Kaprekar number.
The entire list can be found here. Each number has its own meaning.