Matching principal and interest method: loan principal: 65,438+0,000,000, assuming annual interest rate: 4.900% and loan life: 20 years; Monthly debt service: 6,544.44 yuan, total debt service: 65,438+0,570,665.6 yuan, and total interest payable: 570,665.6 yuan. The interest paid in 1 month is: 4083.33; The first 1 month repayment principal is: 2461.11; Since then, the monthly interest repayment amount has decreased and the principal has increased. (without considering the adjustment of interest rate in the middle)