How to round/remove trailing “.0” zeros in pandas column?

use astype(np.int64)

s = pd.Series(['', 8.00735e+09, 4.35789e+09, 6.10644e+09])
mask = pd.to_numeric(s).notnull()
s.loc[mask] = s.loc[mask].astype(np.int64)
s

0              
1    8007350000
2    4357890000
3    6106440000
dtype: object