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Prime Factorization Calculator

Break any number into its prime factors

Factorization

2^3 × 3^2 × 5

Divisors

24

Prime

No

Works best with numbers up to 10 billion. Larger numbers may take a moment.

Prime Factorization

360 = 2^3 × 3^2 × 5

Unique Primes

3

Total Divisors

24

Sum of Divisors

1,170

Is Prime?

No

Prime Factors

23

= 8

32

= 9

5

Formulas Used

Fundamental Theorem of Arithmetic

n = p1^a1 × p2^a2 × ... × pk^ak

Every integer n > 1 can be written uniquely as a product of prime powers, where p1 < p2 < ... < pk are primes and each ai >= 1.

Where:

n= The number to factorize
pi= Distinct prime factors
ai= Exponent (how many times pi divides n)

Number of Divisors

d(n) = (a1 + 1)(a2 + 1)...(ak + 1)

The total count of positive divisors of n, derived from its prime factorization.

Where:

d(n)= Total number of divisors of n
ai= Exponent of the i-th prime factor

Sum of Divisors

σ(n) = Π (pi^(ai+1) - 1) / (pi - 1)

The sum of all positive divisors of n, computed from its prime factorization.

Where:

σ(n)= Sum of all divisors of n
pi= i-th prime factor
ai= Exponent of pi in the factorization

Example Calculations

1Factorize 360

Inputs

Number360

Result

Factorization2³ × 3² × 5
Total Divisors24
Sum of Divisors1,170
Is PrimeNo

360 ÷ 2 = 180, 180 ÷ 2 = 90, 90 ÷ 2 = 45, 45 ÷ 3 = 15, 15 ÷ 3 = 5. Result: 2³ × 3² × 5. Divisors: (3+1)(2+1)(1+1) = 24.

2Factorize 84

Inputs

Number84

Result

Factorization2² × 3 × 7
Total Divisors12
Sum of Divisors224
Is PrimeNo

84 ÷ 2 = 42, 42 ÷ 2 = 21, 21 ÷ 3 = 7. Result: 2² × 3 × 7. Divisors: (2+1)(1+1)(1+1) = 12.

3Check prime: 97

Inputs

Number97

Result

Factorization97 (prime)
Total Divisors2
Sum of Divisors98
Is PrimeYes

97 is not divisible by 2, 3, 5, or 7 (7² = 49 < 97 < 100 = 10²). The next prime to test would be 11, but 11² = 121 > 97, so 97 is prime.

Frequently Asked Questions

Q

What is prime factorization?

Prime factorization is expressing a number as a product of prime numbers. Every integer greater than 1 has a unique prime factorization (Fundamental Theorem of Arithmetic). For example, 360 = 2^3 × 3^2 × 5.

  • 360 = 2³ × 3² × 5 (three distinct primes)
  • 100 = 2² × 5² (two distinct primes)
  • Every integer > 1 has a unique factorization
  • Primes are the "atoms" of multiplication
  • Guaranteed by the Fundamental Theorem of Arithmetic
NumberPrime FactorizationUnique Primes
122² × 32
602² × 3 × 53
3602³ × 3² × 53
10002³ × 5³2
Q

How do you find prime factors step by step?

Use trial division: start by dividing by the smallest prime (2), then 3, 5, 7, and so on. Keep dividing by the same prime until it no longer divides evenly, then move to the next. Stop when the quotient is 1.

  • Start with the smallest prime: 2
  • Divide repeatedly until 2 no longer divides evenly
  • Move to next prime: 3, then 5, 7, 11...
  • Stop when quotient reaches 1
  • Example: 360 ÷ 2 = 180 ÷ 2 = 90 ÷ 2 = 45 ÷ 3 = 15 ÷ 3 = 5
StepDivisionResult
1360 ÷ 2180
2180 ÷ 290
390 ÷ 245
445 ÷ 315
515 ÷ 35 (prime, done)
Q

How do you find all divisors from the prime factorization?

If n = p1^a1 × p2^a2 × ... then the total number of divisors is (a1+1)(a2+1).... Each divisor is formed by choosing an exponent from 0 to ai for each prime pi. For 360 = 2^3 × 3^2 × 5, there are (3+1)(2+1)(1+1) = 24 divisors.

  • Total divisors = (a1+1) × (a2+1) × ... for each prime power
  • 360 = 2³ × 3² × 5: divisors = 4 × 3 × 2 = 24
  • 100 = 2² × 5²: divisors = 3 × 3 = 9
  • Each divisor picks a power of each prime from 0 to max
NumberFactorizationDivisor Count FormulaCount
122² × 3(2+1)(1+1)6
3602³ × 3² × 5(3+1)(2+1)(1+1)24
10002³ × 5³(3+1)(3+1)16
Q

What is a prime number?

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. The first primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29. The number 2 is the only even prime.

  • 2 is the smallest and only even prime number
  • 1 is NOT prime (by convention since 1800s)
  • First 10 primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29
  • There are infinitely many primes (proved by Euclid)
  • To check primality, test divisors up to the square root
NumberPrime?Reason
2YesOnly divisors are 1 and 2
15No15 = 3 × 5
17YesNot divisible by 2, 3, or 4 (4² > 17)
91No91 = 7 × 13

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Last Updated: Mar 9, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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