What's so special about this number?

Tells you what's so special about every number between 0 and 9999,

23 is the smallest number of integer-sided boxes that tile a box so that no two boxes share a common length.


(Except 9995 and 9996 are the same! Both have a square formed by inserting a block of digits inside itself! That's their only claim to fame? Maybe the website should have stopped at 9994.)