| Atomic Mass | Mass Excess |
| 257.095534714365 amu | 88.990 MeV |
| Level energy (MeV) | Spin & parity | Half-life | Mode of decay | Branch ratio (%) | Decay energy (MeV) |
| Ground state | (7/2-) | 5.52 H 0.05 | EC | 85 | 0 |
| Ground state | (7/2-) | 5.52 H 0.05 | A | 15 | 7.558 |
| Ground state | (7/2-) | 5.52 H 0.05 | SF | <1.00 | 0 |
| Decay mode | Half-life | Gamma-ray energy (keV) | Intensity (%) |
| A | 5.52 H 0.05 | 325.10 | 2.5+- 0.6 |
| A | 5.52 H 0.05 | 371.40 | 11.7+- 2.5 |