\[\frac{27^{2} \cdot 9^{4}}{81^{2}} = \frac{\left( 3^{3} \right)^{2} \cdot \left( 3^{2} \right)^{4}}{\left( 3^{4} \right)^{2}} =\]
\[= \frac{3^{6} \cdot 3^{8}}{3^{8}} = 3^{6} = 729.\ \]