Since Gangnam Style hit a high number of views recently, the YouTube mobile app now must use a 64 bit integer to count views!
https://plus.google.com/app/basic/stream/z13usxvqwwmqyrnty22hyldhykbzshkd2
thats bloody optimistic of them 
32 bits would still be suitable for 99% of the videos
34 bits would be more than enough
35 exessive
but 64 - they better plan on being around long after the end of the universe