Each of these numbers is unambiguously X to the Yth power, for integer X and Y. You just have to remember that any number raised to the first power equals itself:
Then you take the Yth letter of X (written out) to get the answer, ITSELF.
I guess "unambiguously" is the wrong word. You could interpret 2,197 as 2,197 to the 1st power and so on, and extract the answer TTSSOF instead. But don't do that.