Is 147 a Prime Number?

Did you know 147 isn’t a prime number? But why? Let us look at the rules a number has to follow to be a prime number to be a prime number.

• It should have only 2 factors: 1 and itself.

• It should have just 2 divisors.

In the rules which satisfy the 2 above, every number that comes next is of a prime number.

We could find that a number is prime if it has 2 factors only, 1 and the number itself. It means that a number, not satisfying these conditions, cannot be a prime number. However, there are pretty simple methods to determine whether a number is prime or not:

• Count Divisor Method

• Divisibility Test

• Prime Number Table

• Prime Factorization

Let's see how each of these tests helps us in finding prime numbers.
 

The name implies: We’re counting how many divisors a given number has, and then saying that number is prime. It is easy to learn. With that said, let’s see what steps are there in this method.

• Divisors of 147: 1,3,7,21,49 and 147.

• Number of divisors: 6

We can see that number 147 has six divisors. And we see that it doesn’t fulfill the criteria needed for a prime number. So it is not a prime number.
 

Let's check 147 is divisible by how many numbers. If 147 is divisible by even one of the numbers, then it will not be a prime number. Let's check the divisibility with 2,3,5 and 7. 

• That is, any number ending in an even number is divisible by 2. And 147 ends with an odd number. Actually, 7 is not a multiple of 2, so it is an odd number. So that 147 will not be divisible by 2 and it is not a prime number.

• The sum of the digits of the number 147 is 12. Now, in order to be divisible by 3, the sum of the digits needs to be a multiple of 3. Since 12 is a multiple of 3. Therefore, 147 is divisible by 3.

• It does not end in 0 or 5. To be divisible by 5 a number should end in 0 or 5. So, 147 cannot be divided by 5.

• We know how to see whether 147 is divisible by 7. Let's simply glance at the last digit, which is 7. We have doubled that 7 to get 14, then subtract the other digit, which is 14. So, we do 14 – 14 = 0. If the difference is 0, that means that the number is divisible by 7.

We see that 147 is exactly divisible by two of the above numbers. Hence, 147 is not a prime number.
 

Here, we will be using a chart that will contain all the prime numbers between 1 and 100. If the given number appears in the list, it is not a prime number. 
 

We can see that 147 does not appear here. So, it is not a prime number.

This method is used to break huge numbers into smaller numbers and find the prime factors of the given number.

We know the prime factors of 147 are 7 and 3. Since there are more than two factors for 147, we can not call 147 a prime number.
 

• Test of divisibility: The test is how many numbers are divisible by the number. For example, 14. Doing the divisibility test gets this to be divisible by both 1, 2 and 7.

• Multiple-The product we get while multiplying a number with another number. Example:- 10×2=20, 10×3=30. Here, 20 and 30 are multiples of 9.

• Composite number: The number which possesses more than 2 factor is named as composite number. Like, example- 18 is factored into 2×32, thus it is a composite number.

• Factor- A number, if multiplied with another number, gives us the required number.Example, 3×2=6, 3×3=9. In that, 2 and 3 are factors.