21171+4001
- Unique Name: 21171+4001SEI1489AC
- RA: 21 17 04.75
- Dec: +40 01 24.6
- Discoverer: SEI
- Discoverer Number: 1489
- Components: AC
- First year: 1895
- Last year: 2012
- Observations: 6
- First position angle: 103
- Last position angle: 102
- First separation: 16.3
- Last separation: 16.6
- Mag first component: 9.7
- Mag second component: 12.7
- Spectral type: A0
- Primary proper motion RA: 5
- Primary proper motion DEC: 0
- Secondary proper motion RA: 8
- Secondary proper motion DEC: 0
- Durchmusterung:
- Notes: