Number Gossip

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Unique Properties of 197

  • 197 is the total sum of the digits of all two digit primes
  • 197 is the smallest cyclic but not permutable prime (its cyclic rotations - 971 and 719 - are primes, but there exists a permutation - 791 or 917 - that is composite)
  • 197 is the only three-digit prime Keith number. Keith numbers have the following rare property: form the sequence with the digits of n. If the total number of digits is n then later terms are sums of t previous terms. Then number n belongs to the sequence
  • 197 is the smallest multidigit number which is a sum of repdigits of its digits (197 = 111 + 9 + 77)

Common Properties of 197