Answer
$$4.3 \times 10^{9} \mathrm{kg} / \mathrm{s}
$$
Work Step by Step
Let $\quad$
$\quad\quad$ mass of the Sun is $M$
$\quad\quad$ time is $t$
$\quad\quad$ and the energy radiated to that time be $E$.
Therefore, power output will be:
$$
P=d E / d t=(d M / d t) c^{2}
$$
where $E=M c^{2}$ is used. At present time,
$$
\frac{d M}{d t}=\frac{P}{c^{2}}=\frac{3.9 \times 10^{26} \mathrm{W}}{\left(2.998 \times 10^{8} \mathrm{m} / \mathrm{s}\right)^{2}}=4.3 \times 10^{9} \mathrm{kg} / \mathrm{s}
$$
