i) The standard form of a natural number $\text{N}\left(>\text{1}\right)$ is $N=p_1{}^{n_1}.p_2{}^{n_2}.p_3{}^{n_3}\mathrm{.........}{p}_k{}^{n_k}$

Where $p_1.p_2.p_3\mathrm{.......}{p}_k$  are distinct primes and $n_1,n_2\mathrm{.......},n_k$  are positive integers.

ii) If $N=p_1{}^{n_1}.p_2{}^{n_2}.p_3{}^{n_3}\mathrm{.........}{p}_k{}^{n_k}$ , then the number of divisors of $\text{N}$  [where $p_1,p_2,p_3,p_4,\mathrm{........}{p}_k$  are

distinct primes] is $d\left(N\right)=(n_1+1)(n_2+1)(n_3+1)\mathrm{.....}(n_k+1)$

iii) The sum of divisors of a natural number, $\sigma \left(N\right)=\left(\frac{p_1{}^{n_1+1}-1}{p_1-1}\right)\left(\frac{p_2{}^{n_2+1}-1}{p_2-1}\right)\mathrm{.............}\left(\frac{p_k{}^{n_k+1}-1}{p_k-1}\right)$