You can easily convert 21 kilometers into miles using each unit definition:
With this information, you can calculate the quantity of miles 21 kilometers is equal to.
In 21 km there are 13.048795 mi.
Which is the same to say that 21 kilometers is 13.048795 miles.
Twenty-one kilometers equals to thirteen miles. *Approximation
Performing the inverse calculation of the relationship between units, we obtain that 1 mile is 0.076635429 times 21 kilometers.
A mile is zero times twenty-one kilometers. *Approximation