PRIME FACTORS OF 21
The prime factors of 21 are 3 and 7.
Factor trees can be used to identify the prime factors of a number. The diagram below shows the factor tree of 21.
Prime factors are the numbers at the endpoints. For 21, these numbers are 3 and 7.
The prime factorization of 21 is 3 × 7.
21 is a composite number.
A prime factor is a factor that is prime. Prime factors can be identified by checking the endpoints of a factor tree.