If the points with position vectors $\alpha \overline{i}+10\overline{j}+13\overline{k},$ $6\overline{i}+11\overline{j}+11\overline{k}$, $\frac{9}{2}\overline{i}+\beta \overline{j}-8\overline{k}$  are collinear then ${\left(19\alpha -6\beta \right)}^2$  is equal to