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 239

  • 239 is the smallest number such when it is summed with the product of its digits generates a nontrivial permutation of its digits (239 + 2*3*9 = 293)
  • 239 The smallest prime p such that the decimal period of 1/p is 7
  • An article in Math World on number 239
  • 239 is the largest integer that cannot be written as a sum of 8 or fewer cubes (the only other number is 23)
  • This prime number appears in one of the earliest known geometrically converging formulas for computing Pi: Pi/4 = 4 arctan(1/5) - arctan(1/239)
  • 239 is the smallest number n such that sum of reciprocals of terms in the period of the continued fraction for square root of n is an integer

Common Properties of 239