Prime Factorize — 素因数分解ツール

Prime factorization and number theory tool. Runs entirely in the browser with zero dependencies and no build step.

Live demo: https://sen.ltd/portfolio/prime-factorize/

Features

• Prime factorization — e.g. 360 = 2³ × 3² × 5
• All divisors listed in ascending order
• Divisor count σ₀(n) and sum of divisors σ(n)
• Primality test — deterministic Miller-Rabin for large numbers (up to Number.MAX_SAFE_INTEGER = 2⁵³ − 1)
• Next prime / previous prime
• Euler's totient φ(n)
• GCD and LCM with a second number
• Perfect / abundant / deficient number classification
• Factorization tree visualization
• History of recent calculations (localStorage)
• Japanese / English UI toggle
• Dark / light theme

Usage

# Serve locally (no build required)
npm run serve
# Open http://localhost:8080

Run tests

node --test tests/prime.test.js
# 75 tests, 0 failures

Tech

• Vanilla JS (ES modules), HTML, CSS
• No framework, no build step
• node:test built-in runner for tests

Number range

Supports positive integers up to Number.MAX_SAFE_INTEGER (9,007,199,254,740,991 ≈ 9×10¹⁵). Primality of large numbers uses a deterministic Miller-Rabin test with 12 witnesses, which is proven correct for all integers in this range.

License

MIT © 2026 SEN LLC (SEN 合同会社)

Links

• 🌐 Demo: https://sen.ltd/portfolio/prime-factorize/
• 📝 dev.to: https://dev.to/sendotltd/prime-factorization-with-deterministic-miller-rabin-up-to-1024-2jj