Looking at sum of squares product

Find myself intrigued a bit at looking at how sums of squares can multiply to give another sum of squares, like with:

(46² + 48² + 72²)(172² + 258² + 430² + 602² +1762²) = 

            615² + 3075² + 14145² + 15990²  + 188497²   =  77⁴*2¹⁰

Just like to stare at it for some reason.