No 21 is not a factor of 24. In order for a number to be a factor of another number, x number times n number must equal the number you are trying to factor.
Below is a self made image that explains factoring and shows you how to factor 24.
The highest common factor of 21 and 24 is 3.
the greatest common factor for 21 and 24 is 3.
The Greatest Common Factor of 21, 24, 14: 1
The greatest commonfactor(gcf) of 24 and 21 is 3
The greatest factor common to both 21 and 24 is 3.
21= 1,3,7 56= 1,2,2,2,7 24= 1,2,2,2,3
The GCF of 21, 24, and 36 is 3.
The GCF is 3.
3
The GCF is 3.
The GCF is: 3
The highest common factor is 3.