Paul McCartney, John Lennon, George Martin and Max Martin rank among the most successful writers and producers over the chart's history.

Paul McCartney and John Lennon photographed in 1964.

David Redfern/Redferns

Among recording artists, The Beatles boast the most No. 1 singles in the Billboard Hot 100’s history: 20. Mariah Carey ranks second, and paces all soloists, with 19 leaders.

Who has the most No. 1s among songwriters and producers?