**The Program in C++ Program to Check if Number is Mersenne number or not is given below:**

```
#include <iostream>
#include <cmath>
using namespace std;
bool isMersenneNumber(int n) {
int m = log2(n + 1);
return pow(2, m) - 1 == n;
}
int main() {
int n;
cout << "Hello Codeauri Family, Enter a number here to check whether the number is mersenne number or not!: \n";
cin >> n;
if (isMersenneNumber(n)) {
cout << n << " is a Mersenne number." << endl;
} else {
cout << n << " is not a Mersenne number." << endl;
}
return 0;
}
```

## Output:

Hello Codeauri Family, Enter a number here to check whether the number is mersenne number or not!:

127

127 is a Mersenne number.

## Pro-Tips**💡**

This program implements a function `isMersenneNumber`

to check if a number is a Mersenne number.

The function uses the formula `m = log2(n + 1)`

to calculate the exponent `m`

and returns `true`

if `n`

is equal to `pow(2, m) - 1`

.

The `main`

function prompts the user to enter a number and calls the `isMersenneNumber`

function with the input.

If the function returns `true`

, the number is a Mersenne number and the program prints a message to that effect.

If the function returns `false`

, the number is not a Mersenne number and the program prints a message to that effect.

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