What is my age?

Question

I'm nine, but me is more than three hundred.

You could've been twenty one.

But you are actually around seventeen thousands.

And all of us are more than half a million.

What is my age?

Answer 1

This puzzle can be understood by

considering each word as a number written in base 26, with the obvious correspondence of letters to digits ($A\rightarrow1,\dots,Z\rightarrow26$).

I'm nine, but me is more than three hundred.

$I=9$ and $ME=(13*26)+5=343>300$.

You could've been twenty one.

"You" in textspeak is U, and $U=21$.

But you are actually around seventeen thousands.

$YOU=(25*26^2)+(15*26)+21=16900+390+21=17311\approx17000$.

And all of us are more than half a million.

Less sure about this one, but $ALL OF=26^4+(12*26^3)+(12*26^2)+(15*26)+6=456976+210912+8112+390+6=676396>500000$. (Using ALLOFUS would be a more obvious choice, and of course still more than half a million, but so much more that the choice of "half a million" in this line would be weird.

What is my age?

I guess it's

either $MY=(13*26)+25=363$ or $AGE=26^2+(7*26)+5=863$.