Factors of 991: Prime Factorization, Methods, and Examples

The number 991 become not a perfect square number and it has only factors 1 and 991 as well an odd number because it not be divisible by 2 and is said to be a prime number because of only 2 factors.

Factors Of 991

Factors of 991

Here are the factors of number 991.

Factors of 991: 1 and 991

Negative Factors of 991

The negative factors of 991 are similar to its positive aspects, just with a negative sign.

Negative Factors of 991: -1 and -991

Prime Factorization of 991

The prime factorization of 991 is the way of expressing its prime factors in the product form.

Prime Factorization: 1 x 991

In this article, we will learn about the factors of 991 and how to find them using various techniques such as upside-down division, prime factorization, and factor tree.

What Are the Factors of 991?

The factors of 991 are 1 and 991. These numbers are the factors as they do not leave any remainder when divided by 991.

The factors of 991 are classified as prime numbers and composite numbers. The prime factors of the number 991 can be determined using the prime factorization technique.

How To Find the Factors of 991?

You can find the factors of 991 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 991, create a list containing the numbers that are exactly divisible by 991 with zero remainders. One important thing to note is that 1 and 991 are the 991’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 991 are determined as follows:

\[\dfrac{991}{1} = 991\]

\[\dfrac{991}{991} = 1\]

Therefore, 1 and 991 are the factors of 991.

Total Number of Factors of 991

For 991, there are two positive factors and two negative ones. So in total, there are four factors of 991. 

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 991 is given as:

Factorization of 991 is 1 x 991.

The exponent of 1 and 991 is 1.

Adding 1 to each and multiplying them together results in 2.

Therefore, the total number of factors of 991 is four. Two are positive, and two 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 991 by Prime FactorizationFactor of 991 by Prime Factorization

The number 991 is a prime 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 991 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 991, 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 991 can be expressed as:

991 = 1 x 991

Factors of 991 in PairsFactor of 991 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 991, the factor pairs can be found as:

1 x 991 = 991

The possible factor pairs of 991 are given as (1, 991).

All these numbers in pairs, when multiplied, give 991 as the product.

The negative factor pairs of 991 are given as:

-1 x -991 = 991

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 and -991 are called negative factors of 991.

The list of all the factors of 991, including positive as well as negative numbers, is given below.

Factor list of 991: 1, -1, 991, and -991

Factors of 991 Solved Examples

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

Example 1

How many factors of 991 are there?


The total number of Factors of 991 is two.

Factors of 991 are 1 and 991.

Example 2

Find the factors of 991 using prime factorization.


The prime factorization of 991 is given as:

991 $\div$ 1 = 991

991 $\div$ 991 = 1 

So the prime factorization of 991 can be written as:

1 x 991 = 991

Factors of 990|Factors List| Factors of 992