TypeError: 'int' object has no attribute '__getitem__'

I have a data frame with different identification numbers and I am trying to format it in two sections, if it has more than 10 digits the format is: 123.456.789-0, if it is different to 10 digits (less or more) the format is : 123,456,789 / 123,456,789,000

for i in range(0, len(mydataset_df.NIT)):
    print 'esto es i =', i
    number = int(mydataset_df.iloc[i]['NIT'])
    length = len(str(number))
    if length == 10:
        nit = number[:-1]
        dv = int(number[-1:])
        nit = format(int(identification), ',d').replace(',', ".")+ "-" + str(dv)
        mydataset_df.loc[i,'NIT'] = nit
        print nit
    else:
        number = format(int(number), ',d').replace(',', ".")
        mydataset_df.loc[i,'NIT'] = number
        print number
    print 'La cantidad de caracteres son:',length
    print mydataset_df.loc[i,'razon_social']
    print '-----------------------'

The error message is:

TypeError: 'int' object has no attribute '__getitem__'

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