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1isn't prime or composite. So 2,3,5,7,11,13,17,19 are all prime because there only factors are 1 and itself.

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Q: What are the prime numbers from 1 to 21?
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Related questions

What are all the prime numbers from 1-21?

The prime numbers from 1 to 21 are 2, 3, 5, 7, 11, 13, 17, and 19.


What prime numbers 21?

A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite. 21 is composite.


Is 21 prime or not prime?

21 is not a prime number. It is divisible by 3 and 7, in addition to 1 and itself.


How many 2 digit prime numbers are there?

there are 50 prime numbers between 1-100 and of them 2,3,5,7 are single digit so that would leave 46 double digit prime numbers between 1-100


Is 21 and 67 a pair of prime numbers?

67 is a prime number, but 21 isn't. A prime number can only be evenly divided by '1' and itself. 21 can be evenly divided by 1, 3, 7, and 21.


Are these numbers prime or composite 21?

21 is a composite number. A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.


Are 4 and 21 relatively prime?

Yes, 4 and 21 are relatively prime. Numbers that are relatively prime only have the number 1 as a common factor. That is the case with 4 and 21.


What is the prime numbers of 21?

Do you mean, "What is the prime factorization of 21?"


Is 21 and 89 a pair of prime numbers?

21 is not prime.


What is the gcf of 14 21 and 8?

1. These numbers are co-prime


Are prime numbers same as odd numbers?

No.Prime numbers are numbers that can only be divided evenly by itself and 1.For example, the number 7 can only be divided by 7 and 1.Odd numbers are numbers that end in (or are) 1, 3, 5, 7, or 9.For example, the number 21 is odd since it ends in a 1, but it is not prime because itcan be divided by 1, 21, 7, and 3. (7 times 3 = 21.)2 is a prime number and is even not odd - it is the only even prime number.


What numbers have an HCF of 1?

An HCF is the product of any common prime factors of two numbers. If two numbers have no common prime factors, then the HCF will be 1. For example, 10 and 21. The prime factors are 2x5 and 3x7. There is nothing in common, and so the HCF of 10 and 21 is 1. Two consecutive numbers will always have the HCF of 1.