Prime Factorization Tree

Decompose into prime factors

CalculatorsFreeNo Signup
4.6(327 reviews)
All Tools

Loading tool...

About Prime Factorization Tree

A prime factorization calculator that decomposes any positive integer into its prime factors. Shows the factorization in exponent form (e.g., 360 = 2³ × 3² × 5), lists all prime factors, counts total divisors, and computes the sum of divisors. All calculations are client-side. Essential for number theory, cryptography, and math education.

Prime Factorization Tree Features

  • Factor tree
  • Exponent form
  • Divisor count
  • Sum of divisors
  • Up to 10⁹
Every integer > 1 has a unique prime factorization (Fundamental Theorem of Arithmetic). 360 = 2³ × 3² × 5. The number of divisors is (3+1)(2+1)(1+1) = 24. Sum of divisors: σ(n) = Π(pᵉ⁺¹−1)/(p−1).

How to Use

Enter a positive integer:

  • Input: Any integer ≥ 2
  • Output: Prime factorization
  • Extra: Divisor count and sum

Algorithm

Trial division: divide by 2, then odd numbers 3, 5, 7, ... up to √n. Each time a factor is found, divide repeatedly until it no longer divides. Any remainder > 1 is a prime factor.

Fundamental Theorem

Every integer > 1 is either prime or a unique product of primes (up to ordering). This is why primes are the 'atoms' of number theory.

Step-by-Step Instructions

  1. 1Enter a positive integer.
  2. 2View prime factorization.
  3. 3Check exponent form.
  4. 4See divisor count.
  5. 5Review divisor sum.

Prime Factorization Tree — Frequently Asked Questions

Why is 1 not a prime number?+

If 1 were prime, factorizations wouldn't be unique: 6 = 2×3 = 1×2×3 = 1×1×2×3. Excluding 1 preserves the Fundamental Theorem of Arithmetic.

How is divisor count calculated?+

For n = p₁ᵉ¹ × p₂ᵉ² × ..., the number of divisors is (e₁+1)(e₂+1).... Each prime can appear 0 to eᵢ times in a divisor.

Is factoring always fast?+

No! Factoring large numbers (hundreds of digits) is believed to be computationally hard. RSA encryption relies on this difficulty. This tool handles numbers up to ~10⁹ instantly.

Share this tool: