It's like telling your only grandson he's your favorite grandson. 49 is the lowest and only number that can be expressed as the square of 7. But the phrasing makes you think there's a second (or more) number after it.

It's a reference to a story about Ramanujan, who once (remarkably) told G. H. Hardy that 1729 wasn't a boring number because it was the smallest number that could be expressed as the sum of two cubes in more than one way. Sometimes trivial but always erudite in the best way, that was Wes.