Curious dream

Curious dream

I wondered how my mind came up with this dream I had.
I walked across a university campus. Two guys recognized me as a math guy. One of them said,
"Years ago, you impressed us by immediately figuring out what is special about the number 1764."
I pondered it. I could divide it by 4 but wasn't sure that would immediately answer what was so special about 1764.
As I woke up, the answer came to me.
1764 = 1800 - 36 = 18 * (100 - 2) = 18 * 98 = (2*9) * (2*49) = (4*9*49) = (2^2) * (3^2)*(7^2) = (2*3*7)^2 = 42^2
Shades of Hitchhikers Guide to the Galaxy!
1764 is the answer to everything squared!