With this information, you can calculate the quantity of miles per hour 21 knots is equal to.
¿What is the inverse calculation between 1 mile per hour and 21 knots?
Performing the inverse calculation of the relationship between units, we obtain that 1 mile per hour is 0.041379821 times 21 knots.
Which is the same to say that 21 knots is 24.166368 miles per hour.
Twenty-one knots equals to twenty-four miles per hour. *Approximation
A mile per hour is zero times twenty-one knots. *Approximation
