Siri can launch any app. Just say “Launch” and then the name of the app. For example, “Launch Calendar” or “Launch Calculator.” This is really great for those with a lot of apps on their iPhones and iPads (and for those who don’t, but still have trouble finding things).
You can often say “Open” in place of “Launch.” Not always. You’ll have to experiment.
Check out my Seven Super Siri Tips for more.