Antimatter bomb

When a massive particle collides with its corresponding antiparticle, they annihilate, producing photons with energy equal to their rest mass energy.

Imagine that you had $1\text{ g}$ of hydrogen and $1\text{ g}$ of anti-hydrogen. How much energy would you release if you let them collide? Express your answer as an order of magnitude. (That is, give $k,$ when your answer is of the form $a \times 10^k$ joules.)

For comparison, the atomic bomb detonated over Nagasaki released $8.8 \times 10^{13}\text{ J}$.