Is 861 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 that is 1. As 861 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 861 has more than two factors, it is not a prime number. Few methods are used to distinguish between prime and composite numbers. A few methods are: - 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 prime and composite numbers. - 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 861 is prime or composite. Step 1: All numbers are divisible by 1 and itself. Step 2: Divide 861 by 2. It is not divisible by 2, so 2 is not a factor of 861. Step 3: Divide 861 by 3. It is divisible by 3, so 3 is a factor of 861. Step 4: You can simplify checking divisors by finding the root value. We then need to only check divisors up to the root value. Since 861 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 1, which is odd, so 861 is not divisible by 2. - Divisibility by 3: The sum of the digits in the number 861 is 15. Since 15 is divisible by 3, 861 is also divisible by 3. - Divisibility by 5: The unit’s place digit is 1. Therefore, 861 is not divisible by 5. - Divisibility by 7: Using the rule for 7, 861 is not divisible by 7. - Divisibility by 11: Using the rule for 11, 861 is not divisible by 11. Since 861 is divisible by 3, 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 100 in 10 rows and 10 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 from 1 to 100. Since 861 is not on the list of prime numbers, 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 861 as 3 × 287. Step 2: Further factorize 287 into 7 × 41. Step 3: Now we get the product consisting of only prime numbers. Hence, the prime factorization of 861 is 3 × 7 × 41.

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: A natural number greater than 1 that has no positive divisors other than 1 and itself. Divisibility: The ability of one number to be divided by another without leaving a remainder. Prime factorization: Breaking down a number into its basic prime number factors. Co-prime numbers: Two numbers with no common factors other than 1.