The greatest common factor (GCF) of 14 and 21 is 7.
To find the GCF, we first identify the factors of each number. The factors of 14 are 1, 2, 7, and 14, while the factors of 21 are 1, 3, 7, and 21. The next step is to find the common factors between the two sets, which in this case is 1 and 7.
Among the common factors, the highest one is 7. Therefore, the GCF of 14 and 21 is 7. This means that 7 is the largest number that can evenly divide both 14 and 21 without leaving a remainder.