Prime Number Checker

About Prime Number Checker

A fast, browser-based prime number checker that determines whether any positive integer is prime or composite. Uses an optimized trial-division algorithm for small numbers and the deterministic Miller-Rabin primality test for numbers up to 3.3 × 10¹⁴. Instantly shows divisibility factors for composite numbers, the nearest primes above and below, and a mini factorization. Perfect for students, math enthusiasts, competitive programmers, and anyone curious about number theory.

Prime Number Checker Features

• Instant primality test
• Miller-Rabin algorithm
• Nearest prime finder
• Factor list for composites
• Supports large numbers