Denzel wishes to save money to provide for his retirement. Beginning one month from now, he will begin depositing a fixed amount into a retirement savings account that will earn 10% compounded monthly. He will make 420 such deposits. Then, one year after making his final deposit, he will withdraw $85,000 annually for 20 years. The fund will continue to earn 10% compounded monthly. How much should the monthly deposits be for his retirement plan?