Answer
$3.80\times10^{26}W$
Work Step by Step
Assume that the sun radiates uniformly.
Imagine a sphere, centered at the Sun, whose radius equals the Earth’s orbital radius. The $1350 W/m^2$ is the average intensity. This is equal to the sun’s total power, distributed over the surface of the imaginary sphere.
$$I=\frac{P}{A}$$
$$P=IA=(1350\frac{W}{m^2})4\pi(1.496\times10^{11}m)^2$$
$$=3.80\times10^{26}W$$