Factor Calculator

Factors of 1155

The factors of 1155 are 1, 3, 5, 7, 11, 15, 21, 33, 35, 55, 77, 105, 165, 231, 385, and 1155. In total, 1155 has 16 factors. Its prime factorization is 3 × 5 × 7 × 11, and the sum of all its factors is 2304.

All factors of 1155

Here are all 16 factors of 1155, listed from smallest to largest.

1357111521333555771051652313851155

Factor pairs of 1155

These 8 pairs of whole numbers each multiply to give 1155.

1 × 1155 = 1155
3 × 385 = 1155
5 × 231 = 1155
7 × 165 = 1155
11 × 105 = 1155
15 × 77 = 1155
21 × 55 = 1155
33 × 35 = 1155

Prime factorization of 1155

Dividing 1155 by the smallest prime at each step gives its prime factorization:

1155 ÷ 3 = 385
385 ÷ 5 = 77
77 ÷ 7 = 11
11 ÷ 11 = 1
Result: 1155 = 3 × 5 × 7 × 11 = 3 × 5 × 7 × 11

The distinct prime factors of 1155 are 3, 5, 7, 11. To factorize any other number, use the prime factorization calculator.

Factor tree of 1155

A factor tree shows the same prime factorization visually. Each composite branch splits until every endpoint is a prime number.

Factor tree of 115511553385577711
Prime factors are shown in solid indigo. Composite numbers split into their smallest prime and the quotient.

Properties of 1155

Number of factors16
Sum of factors2304
Sum of proper factors1149
Prime factorization3 × 5 × 7 × 11
Prime or composite?Composite
Even or odd?Odd
Perfect square?No
Perfect cube?No
ClassificationDeficient

What makes 1155 interesting

  • 1155 is a composite number, meaning it has more than two factors. It can be written as a product of smaller whole numbers in 8 different ways.
  • 1155 is a deficient number: its proper factors sum to 1149, which is 6 less than 1155 itself.
  • 1155 has 4 distinct prime factors (3, 5, 7, 11), which is why it has so many divisors.

How to find the factors of 1155 yourself

Divide 1155 by each whole number starting from 1. Whenever the division leaves no remainder, both the divisor and the quotient are factors. You only need to test up to √115533.99, because every factor above that pairs with one below it.

1155 ÷ 1 = 1155
1155 ÷ 3 = 385
1155 ÷ 5 = 231
1155 ÷ 7 = 165
1155 ÷ 11 = 105
1155 ÷ 15 = 77
1155 ÷ 21 = 55
1155 ÷ 33 = 35

Reading both columns gives every factor: 1, 3, 5, 7, 11, 15, 21, 33, 35, 55, 77, 105, 165, 231, 385, 1155. The factor calculator does this automatically for any number.

Frequently asked questions about 1155

What are the factors of 1155?

The factors of 1155 are 1, 3, 5, 7, 11, 15, 21, 33, 35, 55, 77, 105, 165, 231, 385, and 1155. That is 16 factors in total, counting both 1 and 1155.

Is 1155 a prime number?

No, 1155 is not prime — it is a composite number with 16 factors. A prime number has exactly two factors, but 1155 is also divisible by 3.

What is the prime factorization of 1155?

The prime factorization of 1155 is 3 × 5 × 7 × 11. Written out in full: 3 × 5 × 7 × 11 = 1155. Its distinct prime factors are 3, 5, 7, 11.

What two numbers multiply to give 1155?

There are 8 pairs of whole numbers that multiply to 1155: 1 × 1155, 3 × 385, 5 × 231, 7 × 165, 11 × 105, 15 × 77, 21 × 55, 33 × 35.

What is the sum of the factors of 1155?

Adding all the factors of 1155 together gives 2304. Excluding 1155 itself, the proper factors sum to 1149.

Is 1155 a perfect square?

No, 1155 is not a perfect square. There is no whole number that multiplies by itself to give 1155. The nearest perfect squares are 1089 and 1156.

What is the largest factor of 1155 other than itself?

The largest factor of 1155 apart from 1155 itself is 385, since 1155 ÷ 385 = 3.

How many factors does 1155 have?

1155 has 16 factors: 1, 3, 5, 7, 11, 15, 21, 33, 35, 55, 77, 105, 165, 231, 385, and 1155. You can verify this from the prime factorization 3 × 5 × 7 × 11: add 1 to each exponent and multiply, giving 2 × 2 × 2 × 2 = 16.

Explore more

Try another number in the factor calculator, break 1155 down further with the prime factorization calculator, or compare 1155 with another number using the GCF calculator and LCM calculator. For divisor counts and sums, see the divisor calculator.