 # Factors of 645: Prime Factorization, Methods, and Examples

The number 645 has a total of 8 factors which makes it a composite number, a number that has more than 2 factors, factors of 646 are the numbers that when divide 645, the remainder is zero. This means that when we multiply two factors the resultant is 645.

### Factors of 645

Here are the factors of number 645.

Factors of 645: 1, 3, 5, 15, 43, 129, 215, and 645

### Negative Factors of 645

The negative factors of 645 are similar to its positive aspects, just with a negative sign.

Negative Factors of 645: -1, -3, -5, -15, -43, -129, -215, and -645

### Prime Factorization of 645

The prime factorization of 645 is the way of expressing its prime factors in the product form.

Prime Factorization: 3 x 5 x 43

In this article, we will learn about the factors of 645 and how to find them using various techniques such as upside-down division, prime factorization, and factor tree.

## What Are the Factors of 645?

The factors of 645 are 1, 3, 5, 15, 43, 129, 215, and 645. These numbers are the factors as they do not leave any remainder when divided by 645.

The factors of 645 are classified as prime numbers and composite numbers. The prime factors of the number 645 can be determined using the prime factorization technique.

## How To Find the Factors of 645?

You can find the factors of 645 by using the rules of divisibility. The divisibility rule states that any number, when divided by any other natural number, is said to be divisible by the number if the quotient is the whole number and the resulting remainder is zero.

To find the factors of 645, create a list containing the numbers that are exactly divisible by 645 with zero remainders. One important thing to note is that 1 and 645 are the 645’s factors as every natural number has 1 and the number itself as its factor.

1 is also called the universal factor of every number. The factors of 645 are determined as follows:

$\dfrac{645}{1} = 645$

$\dfrac{645}{3} = 215$

$\dfrac{645}{5} = 129$

$\dfrac{645}{15} = 43$

$\dfrac{645}{43} = 15$

$\dfrac{645}{129} = 5$

$\dfrac{645}{215} = 3$

$\dfrac{645}{645} = 1$

Therefore, 1, 3, 5, 15, 43, 129, 215, and 645 are the factors of 645.

### Total Number of Factors of 645

For 645, there are 8 positive factors and 8 negative ones. So in total, there are 16 factors of 645.

To find the total number of factors of the given number, follow the procedure mentioned below:

1. Find the factorization/prime factorization of the given number.
2. Demonstrate the prime factorization of the number in the form of exponent form.
3. Add 1 to each of the exponents of the prime factor.
4. Now, multiply the resulting exponents together. This obtained product is equivalent to the total number of factors of the given number.

By following this procedure, the total number of factors of 645 is given as:

Factorization of 645 is 1 x 3 x 5 x 43.

The exponent of 1, 3, 5, and 43 is 1.

Adding 1 to each and multiplying them together results in 16.

Therefore, the total number of factors of 645 is 16. 8 is positive, and 8 factors are negative.

### Important Notes

Here are some essential points that must be considered while finding the factors of any given number:

• The factor of any given number must be a whole number.
• The factors of the number cannot be in the form of decimals or fractions.
• Factors can be positive as well as negative.
• Negative factors are the additive inverse of the positive factors of a given number.
• The factor of a number cannot be greater than that number.
• Every even number has 2 as its prime factor, the smallest prime factor.

## Factors of 645 by Prime Factorization

The number 645 is a composite number. Prime factorization is a valuable technique for finding the number’s prime factors and expressing the number as the product of its prime factors. Before finding the factors of 645 using prime factorization, let us find out what prime factors are. Prime factors are the factors of any given number that are only divisible by 1 and themselves.

To start the prime factorization of 645, start dividing by its most minor prime factor. First, determine that the given number is either even or odd. If it is an even number, then 2 will be the smallest prime factor.

Continue splitting the quotient obtained until 1 is received as the quotient. The prime factorization of 645 can be expressed as:

645 = 3 x 5 x 43

## Factors of 645 in Pairs

The factor pairs are the duplet of numbers that, when multiplied together, result in the factorized number. Factor pairs can be more than one depending on the total number of factors given. For 645, the factor pairs can be found as:

1 x 645 = 645

3 x 215 = 645

5 x 129 = 645

15 x 43 = 645

The possible factor pairs of 615 are given as (1, 615), (3, 215), (5,129), and (15, 43 ).

All these numbers in pairs, when multiplied, give 645 as the product.

The negative factor pairs of 645 are given as:

-1 x -645 = 645

-3 x -215 = 645

-5 x -129 = 645

-15 x -43 = 645

It is important to note that in negative factor pairs, the minus sign has been multiplied by the minus sign, due to which the resulting product is the original positive number. Therefore, -1, -3, -5, -15, -43, -129, -215, and -645 are called negative factors of 645.

The list of all the factors of 645, including positive as well as negative numbers, is given below.

Factor list of 645: 1, -1, 3, -3,  5, -5, 15, -15, 43, -43, 129, -129, 215, 215, 645 and -645.

## Factors of 645 Solved Examples

To better understand the concept of factors, let’s solve some examples.

### Example 1

How many factors of 645 are there?

### Solution

The total number of Factors of 645 is 8.

Factors of 645 are 1, 3, 5, 15, 43, 129, 215 and 645.

### Example 2

Find the factors of 645 using prime factorization.

### Solution

The prime factorization of 645 is given as:

645 $\div$ 3 = 215

215 $\div$ 3 = 43

43 $\div$ 43 = 1

So the prime factorization of 645 can be written as:

3 x 5 x 43 = 645