Reasons
1. Justin Bieber is famous (his songs are bound to reach at least 100,000,000 times played or much more), and Luis Fonsi is too (over 20,000,000 times or more) - (meaning it should probably get 120,000,000 plays +.)
2. It gets on things like (#1 on ITunes song charts, trending on YouTube, US Viral 50, SoundCloud lists, platinums, hot Latin songs, billboard top 100, etc). There are news articles when the song was made, the awards it gets, the new languages it's in, how it's exploded out of control, etc. also it gets played on the radio every single day
3. The collaborations of two cultures have made it possible for English and Spanish speakers to listen to it and make singing covers that explode its popularity.