Annual interest rate =5.39%, monthly interest rate = annual interest rate/12=0.449 17%.

First, calculate the monthly repayment amount.

Formula Monthly repayment amount = loan amount * monthly interest rate /[ 1-( 1+ monthly interest rate)-repayment months]

Monthly repayment amount = 231000 * 0.44917%/[1-(1.44917%)-240]

Monthly repayment amount = 1, 574.70 yuan

Second, calculate the remaining principal after 120.

The formula residual principal = monthly repayment amount *[ 1-( 1+ monthly interest rate)-(remaining months-1)]/ monthly interest rate.

Residual principal =1574.7 * [1-(1+0.44917%)-119]/0.44917.

Residual principal =144,910.36 yuan.

Three. Calculate the one-time repayment amount after 120 installment.

Formula lump-sum repayment amount = {loan amount-monthly repayment amount *[ 1-( 1+ monthly interest rate)-months paid]/monthly interest rate} * (months paid+1)

Total amount = {231000-1574.7 * [1-(1+0.44917%)-120]/0.449/.

One-time repayment amount = 146485.06 yuan.

Results:

Under the assumed conditions, the remaining principal after repayment in 120 installments is144,910.36 yuan; After120th installment repayment, the loan can be paid off by one-time repayment of 146485.06 yuan.

Paying off the loan in advance can save interest of 42,479.23 yuan.