During today’s earnings call, Zynga revealed it had grown to 21 million mobile daily active users, compared to the 12 million DAU it had in Q4 2011.

COO John Schappert says that the bulk of the growth was organically generated by Words With Friends, Scramble With Friends and Zynga Poker. Draw Something, while boasting impressive numbers all on its own, didn’t become a part of Zynga until very late in the quarter — which is why it didn’t account for more of that growth. Mark Pincus explained that the game’s monthly unique users were factored into Zynga’s Q1 2012 earnings; it’s monthly unique paying players were not.

Schappert also pointed out on the call that Zynga Poker — a three-year-old mobile game — finally broke into the No. 1 spot on Android’s Top Grossing chart, having already achieved that distinction on iOS. Apple also recognized Words With Friends in March as the No. 1 free game app of all time.

Read the rest on our sister site, Inside Mobile Apps.