For fiscal year 2020 (starting September 2019), the interest has been calculated to be $479 billion. The vast bulk of that goes to the very rich and to central banks. In other words, it does not get recirculated into the 'real' economy of goods and services, but either stays in bank vaults or is used for financial speculation. Therefore, just as quantitative easing was not inflationary because the banks that the money went to didn't spend the money on goods and services, the money printed to pay for the national debt interest payment, for the most part, would not go into the rest of the economy, and so would not be inflationary.