The song is Adele's fourth No. 1 on the tally and the second from her album 25. Lead single "Hello" reigned for four weeks in December. (Between "Hello" and "Send," second single "When We Were Young" reached No. 13.) Adele previously topped Pop Songs with "Rolling in the Deep," for five weeks in 2011, and "Set Fire to the Rain," for four weeks in 2012.
"Send" led the Adult Pop Songs airplay chart for two weeks in August, where it became Adele's fifth No. 1. On the Billboard Hot 100, the song has reached No. 9 so far. (Check Billboard.com later today for highlights of the latest Hot 100.)
The official video for "Send" premiered during ABC's broadcast of the 2016 Billboard Music Awards May 22. 25 has sold 8.98 million copies in the U.S. since its Nov. 20, 2015, release, according to Nielsen Music.
"Send" also marks the record-extending 36th Pop Songs No. 1 as a writer for one of its co-authors, Max Martin. It's also his record-padding 31st Pop Songs topper as a producer. (Put in perspective among artists, Katy Perry and Rihanna share the mark for the most No. 1s: 11 each. Martin has written nine of Perry's No. 1s, and produced seven.)
All charts will update tomorrow (Sept. 13) on Billboard.com.