You can use the financial function of excel to calculate:

=PMT(7.05%/ 12，20* 12，800000，0，0)=-6226.42

6226.42 yuan per month,

Total principal and interest: 6226.42 * 20 *12 =1494341.83.

Total interest: =1494341.83-800000 = 694341.83.

Any bank is similar.