0 is the additive identity.
1 is the multiplicative identity.
2 is the only even prime.
3 is the number of spatial dimensions we live in.
4 is the smallest number of colors sufficient to color all planar maps.
5 is the number of Platonic solids.
6 is the smallest perfect number.
I found this very interesting...to find more visit this page ;
I went there while reading the february issue of SPECTRUM.
The article was "THINGS YOU MAY NOT KNOW ABOUT NUMBERS" .
really interesting one...just go through it!