(I) A certain tridecimal (base 13) positive integer starts with the digit 2. Moving the 2 from the beginning of the number to its end doubles it.

What is the minimum value of this number?

(II) Determine the general form of a positive integer n such that there does not exist any base-n positive integer, starting with the digit 2, that doubles itself when the digit 2 is shifted from the beginning of the number to its end.