Python code for prime number: Prime numbers are one of the most fundamental concepts in mathematics and programming. Whether you’re a beginner learning Python or preparing for coding interviews, understanding how to check prime numbers efficiently is essential.

In this guide, we’ll explore multiple ways to write Python code for prime numbers, from basic logic to optimized approaches. By the end, you’ll be able to write clean, efficient, and interview-ready code.

Article Name	Python Code for Prime Number: Easy Methods with Examples (Beginner to Advanced)
Publish Date	5/5/2026
What is	Python code for prime number
Requirements	Python installed (3.x recommended)
Author	Codeswithsam

What is a Prime Number?

A prime number is a number greater than 1 that has only two factors:

• 1
• Itself

Examples:

• Prime: 2, 3, 5, 7, 11
• Not Prime: 4, 6, 8, 9

Basic Python Code for Prime Number

Let’s start with the simplest approach.

num = int(input("Enter a number: "))

if num > 1:
    for i in range(2, num):
        if num % i == 0:
            print(num, "is not a prime number")
            break
    else:
        print(num, "is a prime number")
else:
    print(num, "is not a prime number")

📖 Explanation:

• We take input from the user. Loop from 2 to num-1. If any number divides num, it’s not prime. If no divisor is found, it’s prime.

Optimized Python Code (Better Performance)

import math

num = int(input("Enter a number: "))

if num > 1:
    for i in range(2, int(math.sqrt(num)) + 1):
        if num % i == 0:
            print(num, "is not a prime number")
            break
    else:
        print(num, "is a prime number")
else:
    print(num, "is not a prime number")

---

Why This is Faster?

Instead of checking all numbers up to n, we only check up to √n.

This reduces:

Time complexity from O(n) → O(√n)

Python Program to Print Prime Numbers in a Range

start = int(input("Enter start number: "))
end = int(input("Enter end number: "))

for num in range(start, end + 1):
    if num > 1:
        for i in range(2, int(num ** 0.5) + 1):
            if num % i == 0:
                break
        else:
            print(num)

Output Example:

Enter start number: 10
Enter end number: 30

11
13
17
19
23
29

---

Advanced Method: Using Function

Functions make your code reusable and clean.

def is_prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n**0.5) + 1):
        if n % i == 0:
            return False
    return True

num = int(input("Enter number: "))

if is_prime(num):
    print("Prime number")
else:
    print("Not a prime number")

🚀 Benefit:

• Much faster than normal recursion
• Avoids repeated calculations

---

How to Run This Code

Follow these steps:

✅ Step 1: Install Python

Download from official site:
https://www.python.org

✅ Step 2: Use Any Editor

• VS Code
• PyCharm
• Notepad

✅ Step 3: Save File

Save as:

prime.py

✅ Step 4: Run Code

Open terminal and type:

python prime.py

---

FAQ Section

Q1: Is 1 a prime number?

No, 1 is not a prime number.

Q2: What is the fastest way to check prime?

Using √n optimization or advanced algorithms like Sieve of Eratosthenes.

Q3: Why is 2 the only even prime number?

Because all other even numbers are divisible by 2.

Final Thoughts

Writing Python code for prime numbers is a great way to improve your logic-building skills. Starting from simple loops to optimized solutions, you now have a complete understanding of how prime number programs work.

Keep practicing and try implementing more optimized algorithms as you grow.

Important Links

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