Opera Mini is one of the few applications on Android that predate the existence of Android itself. The web browser got its start on Java ME-compatible basic phones, and was later ported to BlackBerry, Symbian, Windows Phone, and eventually iOS and Android. Now the app has passed a major milestone on Google's smartphone platform: 500 million installations.
The Play Store now reports Opera Mini as having over 500,000,000 installations worldwide. That's a significant milestone, but it is worth noting that a portion of that number comes from various deals with phone manufacturers over the years. Opera has previously partnered with Micromax, QMobile, and other companies to include Opera Mini on select phones by default, which bolsters the overall install numbers.
That being said, few non-Google apps have ever joined the 500-million club, which includes members like Pinterest, Telegram, and SwiftKey. By comparison, Opera's apps for scamming low-income people in Africa have around 1-10 million installs.