12332.5 yuan.

1. According to the information provided, the total mortgage loan is 2.3 million, the repayment period is 15 years, and the annual interest rate is 3.765%. In order to calculate the monthly payment, we need to convert the annual interest rate to a monthly interest rate and the repayment period to a number of months. The calculation formula for converting annual interest rate into monthly interest rate is: monthly interest rate = annual interest rate ÷ 12. Therefore, the monthly interest rate is 3.765%÷12=0.31375%.

2. The repayment period is 15 years, ***180 months. The calculation formula of monthly payment is: monthly payment = loan principal × monthly interest rate × (1 + monthly interest rate) ^ number of repayment months ÷ [ (1 + monthly interest rate) ^ number of repayment months - 1]. The loan principal, Substituting the monthly interest rate and the number of repayment months into the formula, the monthly payment is: monthly payment = 2300000×0.0031375×(1+0.0031375)^180÷[(1+0.0031375)^180-1]≈12332.5 yuan.

3. Therefore, the monthly payment for a 2.3 million mortgage with a 15-year interest rate of 3.765% is approximately 12,332.5 yuan.