Surface area of a cube

Let $x$ be the side length of the cube. From the figure, the length of the hypotenuse is $x\sqrt{2}$ . So the area of the largest face is $x(x\sqrt{2})=121\sqrt{2}$ . It follows that,

$x^2=121$

So the surface area of the original cube is,

$S=6x^2=6(121)=$ $\boxed{726}$