You will find that that OEM Denso plug has been discontinued and superseded by a heat range 16 plug (hotter). My 2010 Prius has 575k on it so I have done a few plug changes over the years. Even after 125k these plugs are perfectly serviceable in my operation.
Beware of buying plugs on Amazon, eBay and other third party retailers. Believe it or not there are a lot of counterfeit plugs out there. Especially on these iridiums that retail for 15 bucks a piece. They even have knock-offs that come in convincing looking Toyota boxes.
I have run nothing but the Denso SC20HR11s in mine but seeing as how I do get slight pinging under certain conditions, I don't think I'm interested in going to a hotter plug. I will probably try the NGK laser iridium next time. Oddly enough the recommended NGK plug has a heat range actually colder than the OEM Denso if the cross reference is to be believed.
More important than spark plug changes on these engines is keeping the EGR system cleaned out. That includes the EGR cooler, EGR valve, EGR piping and intake manifold ports. Not a super difficult job but somewhat time consuming. That's also the time to do the PCV valve also since it is behind intake manifold on the block.