minuses used in an exponent are shown as spaces

While editing some formula in Wikipedia (LaTeX) , the minus signs are shown like blank spaces when used between the braces of an exponent.
here’s the code:

begin{alignat}{2} varepsilon_0 & = frac{1}{(4 pi times 10^{-7} , textrm{N/A}^{2}) (299792458 , textrm{m/s})^2}  & = frac{625000}{22468879468420441 pi} , textrm{ F/m}  & approx 8.85418781762039 times 10^{-12} , textrm{F}{cdot}textrm{m}^{-1}  end{alignat}

I’m using hyphen (not dash) and I’m using the minus sign from the Wikipedia signs. Also when I add something like a (!) sign or parentheses to the third or second exponent, it just makes all the minuses appear!
Even when I add () to the start of the code the minuses appear.
Why does this happen?