No, as for example 33 ends with a 3 but it is a composite number because it has more than two factors.
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They are all odd, and they are all prime numbers
9 = 3*3 and so it is not a prime.
No 21 isn't (= 3 x 7) 51 isn't (= 3 x 17) 81 isn't ( = 9 x 9)
No, 8 is an even number. ALL prime numbers are odd numbers (excluding 2), that does not mean, however, that all odd numbers are prime numbers. Prime numbers do not have any divisors, even numbers do. Let's say the this number is 18. We know 1 and 18 are one set of divisors. But there are more: 2 and 9, and 3 and 6, thus concluding it is not a prime number. Short list of prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53... and by now you should have noticed the pattern--all numbers that end in 1, 3, 7, 9 are prime.
The prime numbers from 1 - 5 are 2, 3, and 5.