Derek has just retired, and has 400000 dollars in his retirement account. The account will earn interest at an annual rate of 10 percent, compounded monthly.

At the end of each month, Derek will withdraw a fixed amount to cover his living expenses.

Derek wants his savings to last exactly 20 years. How much money can he withdraw each month?

What is the maximum amount that Derek can withdraw each month if he wants his savings to last indefinitely?