The official Google Android app store has more than 400,000 apps available for download.

According to Distimo, the number of apps in the Android Market has surged since April 2011, when it had 200,000 programs available. It's taken four months since it reached the 300,000 milestone in August 2011, to jump by another 100,000. In total, it's taken the official Android app store 38 months since it was launched in October 2008 to reach the 400,000 mark. However, that's two months more than it took Apple, which reached 400,000 apps in June 2011, after being launched in June 208.

It's worth noting the milestone relates to applications that are currently active in the store. Many applications have been removed by Google or developers, due to infringement of copyright for example.

"Interesting to see is that Android Market has taken 31 months to reach the 200,000 milestone, while Apple only needed 22 months to do this for iPhone apps," Distimo said in a blog.

"However, Android Market needed only four more months to pass the 300.000 milestone, while the App Store for iPhone needed eight more months after Apple hits the 200,000 milestone. Moreover, the gap between the 300,000 and 400,000 milestone is also smaller for the Android Market than for the Apple App Store for iPhone, four and seven months respectively."

Furthermore, just over two thirds (68 percent) of the apps available are free to download now, compared to 60 percent in April last year. In addition, the Android Market has almost more than 100,000 active publishers, which makes an average of 4.1 apps per developer, compared to an average of five apps this time last year.