One of your customers is delinquent on his accounts payable balance. Youve mutually agreed to a repayment schedule of $750 per month. You will charge 2.2 percent per month interest on the overdue balance.

If the current balance is $21,000, how long will it take for the account to be paid off? (Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.)