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 10

  • 10 is the base of our number system
  • In base n, n is always written "10"
  • 10 is the only semi-prime number with the property that the sum as well as the difference of its prime divisors are primes (2 + 5 = 7 and 5 - 2 = 3)
  • 10 is the smallest noncototient, a number that can not be expressed as the difference between any integer and the total of coprimes below it

Rare Properties of 10

Tetrahedral (Pyramidal)

Common Properties of 10

Composite
Deficient
Even
Evil
Happy
Square-free
Triangular