yaworsw/euler-manager

---
:id: 387
:name: Harshad Numbers
:url: https://projecteuler.net/problem=387
:content: "A **Harshad or Niven number** is a number that is divisible by the sum
  of its digits.  \n201 is a Harshad number because it is divisible by 3 (the sum
  of its digits.)  \nWhen we truncate the last digit from 201, we get 20, which is
  a Harshad number.  \nWhen we truncate the last digit from 20, we get 2, which is
  also a Harshad number.  \nLet's call a Harshad number that, while recursively truncating
  the last digit, always results in a Harshad number a _right truncatable Harshad
  number._\n\nAlso:  \n201/3=67 which is prime.  \nLet's call a Harshad number that,
  when divided by the sum of its digits, results in a prime a _strong Harshad number_.\n\nNow
  take the number 2011 which is prime.  \nWhen we truncate the last digit from it
  we get 201, a strong Harshad number that is also right truncatable.  \nLet's call
  such primes _strong, right truncatable Harshad primes_.\n\nYou are given that the
  sum of the strong, right truncatable Harshad primes less than 10000 is 90619.\n\nFind
  the sum of the strong, right truncatable Harshad primes less than 10<sup>14</sup>.\n\n"