Revelation 8:6

8:6 Now the seven angels holding the seven trumpets prepared to blow them.

Revelation 17:9

17:9 (This requires a mind that has wisdom.) The seven heads are seven mountains the woman sits on. They are also seven kings:

Revelation 8:2

8:2 Then I saw the seven angels who stand before God, and seven trumpets were given to them.

Revelation 21:9

The New Jerusalem Descends

21:9 Then one of the seven angels who had the seven bowls full of the seven final plagues came and spoke to me, saying, “Come, I will show you the bride, the wife of the Lamb!”