Number Gossip

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Unique Properties of 14

  • 14 is the largest number for which there are as many composite numbers less than it as there are primes
  • 14 is the lowest even n for which the equation φ(x) = n has no solution, making it the first even nontotient
  • There are 14 distinct combinations of four integers such that the sum of their reciprocals is 1
  • 14 is the smallest positive integer n such that n and 2n end with the same digit
  • 14 is the smallest number such that the sum of factorials of its digits is a square (1! + 4! = 25 = 52)
  • 14 is the largest number of distinct sets obtainable by repeatedly applying the set operations of closure and complement to a given starting subset of a topological space (submitted by Corey Cheever)
  • 14 is the smallest number n such that σ(n) = σ(n+1)
  • 14 is the smallest number such that it and the next number are both semiprimes (14 = 2*7 and 15 = 3*5)

Rare Properties of 14

Catalan

Common Properties of 14

Composite
Deficient
Even
Odious
Square-free