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 2

  • 2 is the smallest prime number
  • 2 is the only even prime number
  • 2 is the only number whose factorial is prime
  • For any polyhedron, 2 is the number of vertices plus the number of faces minus the number of edges
  • The smallest field has 2 elements
  • 2 is the only number that it is its own primorial, as well as its own factorial
  • 2 is the only number that isn't n-polygonal with any n (submitted by Alexey Radul)
  • 2 is the largest deficient factorial (submitted by Alexey Radul)

Rare Properties of 2

Cake
Catalan
Factorial
Fibonacci
Google
Narcissistic
Palindromic prime
Power of 2
Primorial
Pronic (Heteromecic)

Common Properties of 2

Deficient
Even
Lazy caterer
Odious
Palindrome
Practical
Prime
Square-free
Ulam
Untouchable