Extremes with Equilaterals

Geometry Level 5

Two concentric circles with center $O$ have radii of $20$ and $14$ .

Two points $A$ and $B$ are drawn such that $A$ is on the circle of radius $20$ , and $B$ is on the circle with radius $14$ .

A point $P$ is drawn so that $\triangle APB$ is equilateral.

If the maximum possible distance of $OP$ is $M$ , and the minimum is $m$ , then find $M\times m$ .