Get number of sheet excel in python

How get number of sheet in below python example?

file = self.excel_file.decode('base64')

excel_fileobj = TemporaryFile('wb+')
excel_fileobj.write(file)
excel_fileobj.seek(0)

workbook = openpyxl.load_workbook(excel_fileobj, data_only=True)

sheet_number= ???

sheet = workbook[workbook.get_sheet_names()[0]]


for row in sheet.rows:
            print(row[1].value)

sheet_number=????

Any solutin?