how to replace scientific notation in Python

fig = plt.figure(figsize=(10,8))
sns.set(font_scale=2.5)
plt.bar(df_year_quantity['TransactionDate'], df_year_quantity['Quantity'])
plt.yticks([4000000,5000000,6000000,7000000], ['4 000 000','5 000 000','6 000 000' ,'7 000 000'])
plt.show()

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plt.ticklabel_format(useOffset=False, style='plain')