21183+3456
- Unique Name: 21183+3456BU 289AB
- RA: 21 18 18.20
- Dec: +34 55 36.2
- Discoverer: BU
- Discoverer Number: 289
- Components: AB
- First year: 1874
- Last year: 2009
- Observations: 22
- First position angle: 140
- Last position angle: 127
- First separation: 1.0
- Last separation: 0.8
- Mag first component: 9.13
- Mag second component: 9.66
- Spectral type: F8
- Primary proper motion RA: 27
- Primary proper motion DEC: 12
- Secondary proper motion RA: 27
- Secondary proper motion DEC: 12
- Durchmusterung: +34 4373
- Notes: