Finite Group DatabasebetaFinite Group DatabasebetaOrder 21.
4 conjugacy classes of subgroups.
| # | subgroup | G/H | class size | multiplicity | normal? | properties |
|---|---|---|---|---|---|---|
| 1 | C7 | C3 | 1 | 1 | yes | maximal, characteristic, direct product factor, Sylow |
| 2 | C3 | C7 | 1 | 1 | yes | maximal, characteristic, direct product factor, Sylow |
| subgroup | G/H | |
|---|---|---|
| center | G | C1 |
| commutator, Frattini | C1 | G |
| LCS | G ▷ C1 | |
| UCS | C1 ◁ G | |
Splittings G = N ⋊ H with N normal; H ≅ G/N.
| N | H ≅ G/N | type |
|---|---|---|
| 1. C7 | C3 | direct (N × H) |
| 2. C3 | C7 | direct (N × H) |
By isomorphism type — maximal subgroups of the same type appear once, whether or not they are normal.
| subgroup | index |
|---|---|
| C7 | 3 |
| C3 | 7 |