Is 406 a Prime Number?

There are two types of numbers, mostly — prime numbers and composite numbers, depending on the number of factors.

• A prime number is a natural number that is divisible only by 1 and itself. For example, 3 is a prime number because it is divisible by 1 and itself.

• A composite number is a positive number that is divisible by more than two numbers. For example, 6 is divisible by 1, 2, 3, and 6, making it a composite number.
   

Prime numbers follow a few properties like:

Prime numbers are positive numbers always greater than 1. 2 is the only even prime number.

They have only two factors: 1 and the number itself.

Any two distinct prime numbers are co-prime numbers because they have only one common factor, which is 1.

As 406 has more than two factors, it is not a prime number.

The characteristic of a prime number is that it has only two divisors: 1 and itself. Since 406 has more than two factors, it is not a prime number. A few methods are used to distinguish between prime and composite numbers:

• Counting Divisors Method
  
   
• Divisibility Test
  
   
• Prime Number Chart
  
   
• Prime Factorization

The method in which we count the number of divisors to categorize the numbers as prime or composite is called the counting divisors method. Based on the count of the divisors, we categorize numbers as prime or composite. If there is a total count of only 2 divisors, then the number would be prime. If the count is more than 2, then the number is composite. Let’s check whether 406 is prime or composite.

Step 1: All numbers are divisible by 1 and themselves.

Step 2: Divide 406 by 2. It is divisible by 2, so 2 is a factor of 406.

Step 3: Divide 406 by 3. It is not divisible by 3, so 3 is not a factor of 406.

Step 4: You can simplify checking divisors up to 406 by finding the root value. We then need to only check divisors up to the root value.

Step 5: When we divide 406 by 2, 101, and 203, it is divisible by 2, 101, and 203.

Since 406 has more than 2 divisors, it is a composite number.

We use a set of rules to check whether a number is divisible by another number completely or not. It is called the Divisibility Test Method.

Divisibility by 2: The number in the ones' place value is 6.

Six is an even number, which means that 406 is divisible by 2.

Divisibility by 3: The sum of the digits in the number 406 is 10.

Since 10 is not divisible by 3, 406 is also not divisible by 3.

Divisibility by 5: The unit’s place digit is 6.

Therefore, 406 is not divisible by 5.

Divisibility by 11: In 406, the sum of the digits in odd positions is 10, and the sum of the digits in even positions is 0.

This would mean that 406 is not divisible by 11.

Since 406 is divisible by 2, it has more than two factors.

Therefore, it is a composite number.

The prime number chart is a tool created by using a method called “The Sieve of Eratosthenes.” In this method, we follow the following steps.

Step 1: Write 1 to 500 in 10 rows and 50 columns.

Step 2: Leave 1 without coloring or crossing, as it is neither prime nor composite.

Step 3: Mark 2 because it is a prime number and cross out all the multiples of 2.

Step 4: Mark 3 because it is a prime number and cross out all the multiples of 3.

Step 5: Repeat this process until you reach the table consisting of marked and crossed boxes, except 1. Through this process, we will have a list of prime numbers.

406 is not present in the list of prime numbers, so it is a composite number.

Prime factorization is a process of breaking down a number into prime factors. Then multiply those factors to obtain the original number.

Step 1: We can write 406 as 2 × 203.

Step 2: In 2 × 203, 203 is a composite number. Further, break the 203 into 7 × 29.

Step 3: Now we get the product consisting of only prime numbers.

Hence, the prime factorization of 406 is 2 × 7 × 29.

• Composite numbers: Natural numbers greater than 1 that are divisible by more than 2 numbers are called composite numbers. For example, 12 is a composite number because 12 is divisible by 1, 2, 3, 4, 6, and 12.
  
   
• Prime numbers: Numbers greater than 1 with no divisors other than 1 and themselves.
  
   
• Divisibility rules: Guidelines to determine if a number is divisible by another number without actual division.
  
   
• Prime factorization: Breaking down a number into its prime factors.
  
   
• Sieve of Eratosthenes: An ancient algorithm used to find all prime numbers up to any given limit.