21121+4543
- Unique Name: 21121+4543BU 160AB
- RA: 21 12 06.93
- Dec: +45 42 12.6
- Discoverer: BU
- Discoverer Number: 160
- Components: AB
- First year: 1873
- Last year: 2011
- Observations: 14
- First position angle: 155
- Last position angle: 155
- First separation: 60.0
- Last separation: 57.1
- Mag first component: 7.9
- Mag second component: 11.4
- Spectral type: B8V
- Primary proper motion RA: 5
- Primary proper motion DEC: 0
- Secondary proper motion RA: -1
- Secondary proper motion DEC: -3
- Durchmusterung: +45 3442
- Notes: N
