Answer
$$5 \times 10^6 \ MW.$$
Work Step by Step
Since 1 MW =$10^{6}$ W, then 1 W = $10^{-6} $ MW. So we have
$$ 5\times 10^{12} \ W= 5 \times 10^{12} \times 10^{-6} \ MW=5 \times 10^6 \ MW.$$
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