A line passes through A(4,-6,-2) and B(16,-2,4). The point P(a, b, c), where a, b, c are non-negative integers, on the line A B lies at a distance of…

A line passes through $\displaystyle A(4,-6,-2)$ and $\displaystyle B(16,-2,4)$. The point $\displaystyle P(a, b, c)$, where $\displaystyle a$, $\displaystyle b, c$ are non-negative integers, on the line $\displaystyle A B$ lies at a distance of $\displaystyle 21$ units, from the point $\displaystyle A$. The distance between the points $\displaystyle P(a, b, c)$ and $\displaystyle Q(4,-12,3)$ is equal to $\displaystyle \_\_\_\_$.