Divisor Sum of 19,215

Example of Divisor Sum of Integer

$\map {\sigma_1} {19 \, 215} = 38 \, 688$

where $\sigma_1$ denotes the divisor sum function.

We have that:

$19 \, 215 = 3^2 \times 5 \times 7 \times 61$

Hence:

$\ds \map {\sigma_1} {19 \, 215}$

$=$

$\ds \dfrac {3^3 - 1} {3 - 1} \times \paren {5 + 1} \times \paren {7 + 1} \times \paren {61 + 1}$

$\ds $

$=$

$\ds \dfrac {26} 2 \times 6 \times 8 \times 62$

$\ds $

$=$

$\ds 13 \times 6 \times 8 \times 62$

$\ds $

$=$

$\ds 13 \times \paren {2 \times 3} \times 2^3 \times \paren {2 \times 31}$

$\ds $

$=$

$\ds 2^5 \times 3 \times 13 \times 31$

$\ds $

$=$

$\ds 38 \, 688$

$\blacksquare$