Respuesta :

lobster
3 is a factor of 21 but not 7 Bc 21 is a prime number. Which means that is greater than 1 and its self.
eowynrobinson
1, 3, and 21 are all multiples of 21. 21 is a composite number meaning it can be divided by numbers (not 1 or itself) 1 and 7 are factors or 7. 7 is a prime number meaning it can only be divided 1 and itself so the answer to your question would be 3 and 21. Hope it helped! ☺