21128+3907
- Unique Name: 21128+3907SEI1447
- RA: 21 12 48.41
- Dec: +39 06 40.7
- Discoverer: SEI
- Discoverer Number: 1447
- Components:
- First year: 1895
- Last year: 2002
- Observations: 7
- First position angle: 153
- Last position angle: 151
- First separation: 13.5
- Last separation: 13.2
- Mag first component: 9.34
- Mag second component: 12.0
- Spectral type: A5
- Primary proper motion RA: 10
- Primary proper motion DEC: -4
- Secondary proper motion RA: 12
- Secondary proper motion DEC: -4
- Durchmusterung: +38 4395
- Notes: N
