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 69

  • 69 is the smallest strobogrammatic number which is not a palindrome
  • 69 is the largest number out of two (the other being 63) such that the common alphabetical value of its Roman representation is equal to itself (LXIX - 12+24+9+24=69)
  • 10069 - 69 is prime: note that 69 is the smallest number with this property
  • 69 has the interesting property of being the only number whose square and cube contain once and only once all numerals from zero to nine when written in decimal notation: 692 = 4761 and 693 = 328509
  • 69 is the smallest number besides 1 whose sum of divisors equals its reversal (96 = 1 + 3 + 23 + 69)

Common Properties of 69

Composite
Deficient
Lucky
Odd
Odious
Square-free
Ulam