Prime Number Checker API: Complete Developer Guide

Need to check if a number is prime in your application? This guide covers everything about prime number checking via API, including what prime numbers are, primality testing algorithms, and implementation examples in multiple programming languages.

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. Prime numbers are the building blocks of all natural numbers through multiplication.

First prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29...

Primality Testing Algorithms

Different methods to check if a number is prime:

Trial Division

Check divisibility by all numbers up to the square root. Simple but slow for large numbers.

Miller-Rabin Test

Probabilistic test that's efficient for large numbers. Our API uses this for big integers.

Sieve of Eratosthenes

Efficient for finding all primes up to a limit, not for testing individual numbers.

Using the Prime Number API

TinyFn provides a simple endpoint to check prime numbers:

GET https://api.tinyfn.io/v1/math/is-prime?number=17
Headers: X-API-Key: your-api-key

{
  "number": 17,
  "is_prime": true,
  "factors": [1, 17],
  "next_prime": 19,
  "previous_prime": 13
}

Parameters

Code Examples

JavaScript / Node.js

const response = await fetch(
  'https://api.tinyfn.io/v1/math/is-prime?number=17',
  { headers: { 'X-API-Key': 'your-api-key' } }
);
const result = await response.json();
console.log(result.is_prime); // true

Python

import requests

response = requests.get(
    'https://api.tinyfn.io/v1/math/is-prime',
    params={'number': 17},
    headers={'X-API-Key': 'your-api-key'}
)
result = response.json()
print(result['is_prime'])  # True

cURL

curl "https://api.tinyfn.io/v1/math/is-prime?number=17" \
  -H "X-API-Key: your-api-key"

Common Use Cases

• Cryptography: Generate prime numbers for RSA key generation
• Educational Apps: Build math learning tools and games
• Data Validation: Validate prime-based identifiers
• Hash Tables: Use prime numbers for hash table sizing
• Number Theory: Research and mathematical applications

Best Practices

1. Handle edge cases: Numbers less than 2 are not prime
2. Consider size: Very large numbers may require probabilistic tests
3. Cache results: Cache prime checks for frequently tested numbers
4. Use appropriate precision: Be aware of integer overflow for large numbers

Use via MCP

Your AI agent can call this tool directly via Model Context Protocol — no HTTP code needed. Add TinyFn to Claude Desktop, Cursor, or any MCP client:

{
  "mcpServers": {
    "tinyfn-math": {
      "url": "https://api.tinyfn.io/mcp/math/",
      "headers": {
        "X-API-Key": "your-api-key"
      }
    }
  }
}

See all math tools available via MCP in our Math MCP Tools for AI Agents guide.