Number Gossip

(Enter a number and I'll tell you everything you wanted to know about it but were afraid to ask.)

Unique Properties of 21

  • 21 is the smallest number of distinct integer-sided squares needed to tile a square
  • 21 is the number of spots on a standard cubical die (1+2+3+4+5+6)

Rare Properties of 21

Fibonacci

Common Properties of 21

Composite
Deficient
Lucky
Odd
Odious
Square-free
Triangular