You can put this solution on YOUR website! The possible dimensions of the length & width are many within the range of 1 & 504.
Examples:
xy=504
x=504/y
let y=4 then:
x=504/4
x=126
4*126=504
----------
Let y=8 then:
x=504/8
x=63
63*8=504
------------
Let y=12
x=504/12
x=42
42*12=504
-----------
Let y=20
x=504/20
x=25.2
20*25.2=504
------------