What's Special About This Number?
What's Special About This Number? If you know a distinctive fact about a number not listed here, please e-mail me. primes graphs digits sums of powers bases combinatorics powers/polygonal Fibonacci geometry repdigits algebra perfect/amicable pandigital matrices divisors games/puzzles 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 . 7 is the smallest number of sides of a regular polygon that is not constructible by straightedge and compass. 8 is the largest cube in the Fibonacci sequence . 9 is the maximum number of cubes that are needed to sum to any positive integer . 10 is the base of our number system. 11 is the largest known multiplicative persistence . 12 is the smallest abundant number . 13 is the number of Archimedian solids . 17 is the number of wallpaper groups .