------
## 最终结论
```python
def set_Bit_Number(n):
    if n == 0:
        return 0
    msb = 1
    while msb <= n:
        msb <<= 1
    return msb >> 1

# Test cases
assert set_Bit_Number(6) == 4
assert set_Bit_Number(10) == 8
assert set_Bit_Number(18) == 16
```