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 55

  • 55 is the largest number that is both triangular and Fibonacci. By the way, 55 has index ten in either sequence
  • 55 is the smallest multi-digit triangular number which is a palindrome
  • 55 is the product of the smallest sexy prime pair
  • 55 is the only multi-digit Fibonacci number using one digit
  • 55 is the smallest number sandwiched between two numbers that are products for four primes
  • Not counting trivial 1, 55 is the smallest triangular number that is also square-pyramidal

Rare Properties of 55

Fibonacci

Common Properties of 55

Composite
Deficient
Odd
Odious
Palindrome
Square-free
Triangular