Prime Factorization Calculator

Find the prime factorization of any number up to 10,000,000 with a visual factor tree. Also calculates GCD and LCM of two numbers with full working shown.

Prime factorization formulas

GCD(a,b) using Euclidean algorithm: GCD(a,b) = GCD(b, a mod b), repeat until remainder = 0.

LCM(a,b) = (a × b) ÷ GCD(a,b)

Example: GCD(48, 18). 48 = 2×18+12 → GCD(18,12). 18 = 1×12+6 → GCD(12,6). 12 = 2×6+0. GCD = 6. LCM = (48×18)÷6 = 144.

Frequently Asked Questions

What is prime factorization?

Prime factorization is expressing a number as a product of its prime factors. For example, 60 = 2² × 3 × 5.

What is the difference between GCD and LCM?

GCD (Greatest Common Divisor) is the largest number that divides both numbers exactly. LCM (Least Common Multiple) is the smallest number that is a multiple of both. GCD × LCM = product of the two numbers.

What is the Euclidean algorithm?

The Euclidean algorithm finds the GCD by repeatedly replacing the larger number with the remainder of dividing the two numbers, until the remainder is 0.

How do I find the LCM of two numbers?

LCM(a, b) = (a × b) / GCD(a, b). Alternatively, use prime factorization and take the highest power of each prime factor.

Is 1 a prime number?

No — by definition, a prime number has exactly two distinct divisors: 1 and itself. The number 1 has only one divisor, so it is not prime.

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