"We would not be surprised to see Apple sell closer to 1 million iPad2s in the opening weekend," said Wedbush Securities analyst Scott Sutherland.
Best Buy on Friday said some of its outlets ran out of the tablet and its accessories within 10 minutes.
Global Equities Research analyst Trip Chowdhry estimates Apple may have sold three times more iPad 2 in the first two days compared to the previous version.
Most analysts had projected sales of 350,000 to 400,000 iPads in its debut weekend.
The profile of iPad 2 buyer is -- 60 percent existing iPad owners, about 40 percent first time iPad buyers, 100 percent own at-least One Apple Product, Chowdhry wrote.
People prefer AT&T's iPad 2 over Verizon's because AT&T has better customer service, Chowdhry added.
(Reporting by Jennifer Robin Raj; Editing by Saumyadeb Chakrabarty)
Copyright 2011 Thomson Reuters. Click for Restrictions.