Instagram's move to Android has done wonders for the photo sharing app — first it managed to amass five million new users in less than a week, and now its overall userbase has reportedly surpassed 40 million. That number comes from Rakshith Krishnappa, creator of Instagram-viewer Gramfeed, who told TechCrunch that Instagram's API now lists a total of 40,026,379 users. That's a jump of 10 million from when the app first launched on Android, which was just ten days ago. We're not sure what percentage of those new users are on Android, but given the explosive growth of Instagram on the platform, we'd imagine that the majority of them are, though the app did reach number one on the iOS charts this week. The continued growth of Instagram should be welcome news to Facebook, which recently shelled out $1 billion to acquire the company in a deal that took just two days to complete.