The biggest selling and most commercially successful Beatles single was , which was the first Beatles release on their new Apple label and went to #1 in twelve countries.

   Hey Jude / Revolution

Explanation:  As being said, it's a single from the Beatles' first album that was released by Apple. It is well known that this song was written by Paul McCartney, although the song itself is credited to the creative duo Lennon / McCartney. The release of this song by Apple as a record label was also a celebration of the public launch of a new record label. As mentioned, this single was number one on many countries' charts and was released in 1968. It should be noted that this song, with nine weeks at number one on the US Billboard Hot 100, set the record for the longest time spent at number one. It should also be said that the aforementioned Hey Jude song was found together on the single, with the Revolution song recorded on the other side of the single.