There are approximately 700,000 apps on the Android the iOS app stores

"Google Inc said there are about 700,000 applications available for downloading onto mobile devices that run the Android operating system, challenging Apple Inc’s lead in the race for software tools.
That means Google has matched Apple in the number of games, productivity tools and other programs that are usable on handheld electronics, including tablets and smartphones. Apple said last week that its App Store has more than 700,000 apps."

Source:  Businessweek, 29th October 2012