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 13

  • 13 is widely known as the unlucky number (it also happens to be a Lucky number)
  • 13 is the smallest prime which is not a minimal prime
  • Three planes can cut a donut (solid torus) into a maximum of 13 parts
  • 13 is the smallest prime which can be represented as sum of two primes (i.e., 2 + 11) as well as sum of two composite numbers (i.e., 9 + 4)
  • 13 is the smallest emirp
  • 13 is the smallest prime whose sum of digits is square
  • 13 is the number of Archimedian solids
  • Unreasoned fear of the number 13 is termed triskaidekaphobia
  • 13 is the number of times in one century when the date in the format month day and the last two digits of the year can be written with the same digit
  • 13 is the number of intersections of diagonals inside a regular hexagon

Rare Properties of 13

Fibonacci

Common Properties of 13

Deficient
Happy
Lucky
Odd
Odious
Prime
Square-free
Twin
Ulam