# Count total missing values in a dataframe
df.isnull().sum().sum()
# Gives a integer value
In [74]: df.columns[df.isna().any()].tolist()
Out[74]: ['a', 'b']
import pandas as pd
df = pd.DataFrame({'a':[1,2,np.nan], 'b':[np.nan,1,np.nan],'c':[np.nan,2,np.nan], 'd':[np.nan,np.nan,np.nan]})
print(pd.isnull(df).sum())