RSA DECRYPTION when N gives only one prime number

I am getting only 1 prime factor to some power if i factorize N for RSA decryption. So, in this case what will be the value of P and Q. P will be that one Prime Factor and then there is nothing left for Q.

Kindly help me out

If I understand you correctly, you are asking what will happen if you use an encryption method similar to RSA, but with $N = p^k$ for some prime $p$ and arbitrary integer k instead of $N = pq$ for different primes $p$ and $q$.

Such method of encryption will be insecure, because the adversary will be able to compute your secret key $(p, k)$ from $N$ in $O(\log^3N\log\log N)$ the following way:

For every $k'$ from $1$ to $\log_2(N)$ check whether $N$ is a complete $k$-th degree of an integer and compute its $k'$-th root if it is (this can be done in $O(\log^2N\log k')$). The last $k'$ for which this happened to be true is our $k$ and $p$ is the corresponding root.