import numpy as np
import pandas as pd

ds = pd.Series([1, np.nan, 3, 4, 5])

ds

0    1.0
1    NaN
2    3.0
3    4.0
4    5.0
dtype: float64

# ds = ds.astype('int') # will throw ValueError: Cannot convert non-finite values (NA or inf) to integer

ds = ds.astype('float')

ds

0    1.0
1    NaN
2    3.0
3    4.0
4    5.0
dtype: float64

ds = pd.to_numeric(ds, downcast='float')

ds

0    1.0
1    NaN
2    3.0
3    4.0
4    5.0
dtype: float32

# You could see the dtype chagend fro float64 to float32