Factors of 155

How to find the factors of 155

Test every whole number from 1 up to the square root of 155 (√155 ≈ 12.450). Each number that divides evenly gives you two factors at once: the divisor and the quotient.

• 155 ÷ 1 = 155 — so 1 and 155 are factors
• 155 ÷ 2 = 77.5 — not a whole number
• 155 ÷ 3 = 51.667 — not a whole number
• 155 ÷ 4 = 38.75 — not a whole number
• 155 ÷ 5 = 31 — so 5 and 31 are factors
• 155 ÷ 6 = 25.833 — not a whole number
• 155 ÷ 7 = 22.143 — not a whole number
• 155 ÷ 8 = 19.375 — not a whole number
• 155 ÷ 9 = 17.222 — not a whole number
• 155 ÷ 10 = 15.5 — not a whole number
• 155 ÷ 11 = 14.091 — not a whole number
• 155 ÷ 12 = 12.917 — not a whole number

Collecting both numbers from every successful division gives the complete list: 1, 5, 31 and 155.

Prime factorization of 155

Divide by the smallest prime that fits, and keep going until the quotient is 1:

The primes you divided by give 155 = 5 × 31. From the exponents you can also count the factors without listing them: (1 + 1) × (1 + 1) = 4.

Properties of 155

• 155 is a composite number.
• The sum of all its factors is 192; the sum of its proper factors (excluding 155) is 37, which makes it a deficient number (its proper factors add up to less than itself).
• 155 is not a perfect square, so its factors pair up evenly.
• Multiples of 155 include 310, 465, 620, 775 and so on.

Factors vs. multiples

Factors of 155 are the numbers that divide into it; multiples of 155 are the numbers it divides into. Every number has a limited set of factors but infinitely many multiples. To work with any other number, use the factors calculator, or find shared factors with the GCF calculator.