An n-parasitic number (in base 10) is a positive natural number which, when multiplied by n, results in movement of the last digit of its decimal representation to its front. Here n is itself a single-digit positive natural number. In other words, the decimal representation undergoes a right circular shift by one place. For example:
Most mathematicians do not allow leading zeros to be used, and that is a commonly followed convention.
So even though 4 × 25641 = 102564, the number 25641 is not 4-parasitic.