Depends on how much of that revenue was due to the Watch, and what the ASP was. For the range of $1B to $1.5B revenue, and ASPs either at the low or high end (more high end watches = less sales), plus a lot of bands sold, the number of watches can indeed range from about 2.2 to 3.3 million.
As for the oft-mentioned iPad numbers... Cook did NOT say what people think he did.
Here's what Cook actually said:
"To give you a little additional insight, through the end of the quarter, in fact, the Apple Watch sell-through was higher than the comparable launch periods of the original iPhone or the original iPad. "
Notice that he said "sell-through", NOT "sales". That's an entirely different ball of wax. Sell-through to end users is almost always less than the highly publicized sales (shipments) to retailers... often millions less.
Checking back through previous calls, it appears that sell-through on the first iPad quarter might have been around 2.7 million. We also need to figure out what "comparable launch period" means.
He also made this comment, talking about sales increasing over time:
"On the Watch, our June sales were higher than April or May. I realize that's very different than what some of the -- is being written, but June sales were the highest."
Which makes total sense if one understands that online purchases... unlike retailer purchases... are not counted as sales until they arrive at the end consumer. Very few consumers got a watch right away. Instead, more and more people got devices delivered as time went on and production ramped up. So naturally June had the most "sales", even if they were pre-ordered back in April.
This is all part of the verbal sleight-of-hand that Jobs was a master at, and Cook is clearly trying to be a good pupil.