# Composite numbers from 21 to 40

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We say that a number is composite if it has a factor other than 1 and itself. In this article, we list out all the composite numbers between 21 and 40. We then explain why this list includes all the composite numbers lying in between.

### List of composite numbers:

1. 21
2. 22
3. 24
4. 25
5. 26
6. 27
7. 28
8. 30
9. 32
10. 33
11. 34
12. 35
13. 36
14. 38
15. 39
16. 40

#### Why is this the entire list of composite numbers between 21 and 40?

1. 21 is composite because it has factors 1, 3, 7 and 21.
2. 22 is composite because it has factors 1, 2, 11 and 22.
3. 23 is prime because it has only two factors – 1 and 23.
4. 24 is composite because it has factors 1, 2, 3, 4, 6, 8, 12 and 24.
5. 25 is composite because it has factors 1, 5 and 25.
6. 26 is composite because it has factors 1, 2, 13 and 26.
7. 27 is composite because it has factors 1, 3, 9 and 27.
8. 28 is composite because it has factors 1, 2, 4, 7, 14 and 28.
9. 29 is prime because it has only two factors – 1 and 29.
10. 30 is composite because it has factors 1, 2, 3, 5, 6, 10, 15 and 30.
11. 31 is prime because it has only two factors – 1 and 31.
12. 32 is composite because it has factors 1, 2, 4, 8, 16 and 32.
13. 33 is composite because it has factors 1, 3, 11 and 33.
14. 34 is composite because it has factors 1, 2, 17 and 34.
15. 35 is composite because it has factors 1, 5, 7 and 35.
16. 36 is composite because it has factors 1, 2, 3, 4, 9, 12, 18 and 36.
17. 37 is prime because it has only two factors – 1 and 37.
18. 38 is composite because it has factors 1, 2, 19 and 38.
19. 39 is composite because it has factors 1, 3, 13 and 39.
20. 40 is composite because it has factors 1, 2, 4, 5, 8, 10, 20 and 40.

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