Prime String

Last Updated : 11 Jul, 2025

Given a String str , the task is to check if the sum of ASCII value of all characters is a Prime Number or not.

Examples : 

Input  : geeksforgeeks
Output : Yes

Input  : GeeksForGeeks
Output : No

Algorithm  

  1. Calculate the string length
  2. Calculate sum of ASCII value of all characters
  3. Now we can check till n1/2 because a larger factor of n must be a multiple of smaller factor. (Please see Check If the Number is Prime or Not for details)
  4. If the Sum is Prime then print “Yes” otherwise “No”

Now the implementation of above approach given below: 

C++ 
// C++ program to find if string is a
// Prime or not.
#include <bits/stdc++.h>
using namespace std;

// Function that checks if sum 
// is prime or not
bool isPrimeString(string str)
{
    int len = str.length(), n = 0;
    for (int i = 0; i < len; i++)
        n += (int)str[i];

    // Corner cases
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;

    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return false;

    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;

    return true;
}

// Driver code
int main()
{
    string str = "geekRam";
    if (isPrimeString(str))
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
}
Java 
// Java program to find if
// string is a Prime or not.
import java.io.*;

class GFG {
    
    // Function that checks if
    // sum is prime or not
    static boolean isPrimeString(String str)
    {
        int len = str.length(), n = 0;
        for (int i = 0; i < len; i++)
            n += (int)str.charAt(i);
    
        // Corner cases
        if (n <= 1)
            return false;
        if (n <= 3)
            return true;
    
        // This is checked so that we can skip
        // middle five numbers in below loop
        if (n % 2 == 0 || n % 3 == 0)
            return false;
    
        for (int i = 5; i * i <= n; i = i + 6)
            if (n % i == 0 || n % (i + 2) == 0)
                return false;
    
        return true;
    }

    // Driver code
    public static void main (String[] args)
    {
        String str = "geekRam";
        
        if (isPrimeString(str))
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}

// This code is contributed by Ajit.
Python3 
# Python Program to find if string is Prime or not 
# Function that checks if sum is prime or not
def isPrimeString(str1):
    len1 = len(str1)
    n = 0
    for i in range(len1):
        n += ord(str1[i])
    
    # corner cases
    if n <= 1:
        return False
    if n <= 3:
        return True
    
    # This is checked so that we can skip 
    # middle five numbers in below loop
    if n % 2 == 0 or n % 3 == 0:
        return False
    while(i * i <= n):
        if n % i == 0 or n % (i + 2) == 0:
            return False
        i += 6
    return True

# Driver code 
str1 = "geekRam"
if(isPrimeString(str1)):
    print("Yes")
else:
    print("No")

# This code is contributed by simranjenny84
C# 
// C# program to find if string is
// a Prime or not
using System;

class GFG
{

// Function that checks if sum is prime or not 
public static bool isPrimeString(string str)
{
    int len = str.Length, n = 0;
    for (int i = 0; i < len; i++)
    {
        n += (int)str[i];
    }

    // Corner cases 
    if (n <= 1)
    {
        return false;
    }
    if (n <= 3)
    {
        return true;
    }

    // This is checked so that we can skip 
    // middle five numbers in below loop 
    if (n % 2 == 0 || n % 3 == 0)
    {
        return false;
    }

    for (int i = 5; i * i <= n; i = i + 6)
    {
        if (n % i == 0 || n % (i + 2) == 0)
        {
            return false;
        }
    }

    return true;
}

// Driver code 
public static void Main(string[] args)
{
    string str = "geekRam";

    if (isPrimeString(str))
    {
        Console.WriteLine("Yes");
    }
    else
    {
        Console.WriteLine("No");
    }
}
}

// This code is contributed by Shrikant13
PHP 
<?php
// PHP program to find if 
// string is a Prime or not.

// Function that checks 
// if sum is prime or not
function isPrimeString($str)
{
    $len = strlen($str); $n = 0;
    for ($i = 0; $i < $len; $i++)
        $n += (int)$str[$i];

    // Corner cases
    if ($n <= 1)
        return false;
    if ($n <= 3)
        return true;

    // This is checked so that 
    // we can skip middle five
    // numbers in below loop
    if ($n % 2 == 0 || $n % 3 == 0)
        return false;

    for ($i = 5; $i * $i <= $n; $i = $i + 6)
        if ($n % $i == 0 || 
            $n % ($i + 2) == 0)
            return false;

    return true;
}

// Driver code
$str = "geekRam";
if (isPrimeString($str))
    echo "Yes" , "\n";
else
    echo "No" , "\n";

// This code is contributed by aj_36
?>
JavaScript 
<script>

// Javascript program to find if string
// is a Prime or not

// Function that checks if sum is prime or not 
function isPrimeString(str)
{
    let len = str.length, n = 0;
    for(let i = 0; i < len; i++)
    {
        n += str[i].charCodeAt();
    }

    // Corner cases 
    if (n <= 1)
    {
        return false;
    }
    if (n <= 3)
    {
        return true;
    }

    // This is checked so that we can skip 
    // middle five numbers in below loop 
    if (n % 2 == 0 || n % 3 == 0)
    {
        return false;
    }

    for(let i = 5; i * i <= n; i = i + 6)
    {
        if (n % i == 0 || n % (i + 2) == 0)
        {
            return false;
        }
    }
    return true;
}

// Driver code
let str = "geekRam";

if (isPrimeString(str))
{
    document.write("Yes");
}
else
{
    document.write("No");
}

// This code is contributed by decode2207

</script>

Output
No

Time Complexity: O(n)
Auxiliary Space: O(1), As constant extra space is used.

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