According to the Federal Reserve, there are over 1.7 trillion U.S. Dollars in circulation.
This number has been drastically increasing throughout the last few years, mostly due to programs such as Quantitative Easing. As of 2016, QE programs have ended and the Fed's balance sheet is shrinking, but M2 money supply still remains at elevated levels.
What is the Size of our National Debt?
What is Currency in Circulation?