PROGRAMMING:Function returns the sum of true divisors of integers

Write a function to return the true divisor sum of integers, the main function input integer n, output the true divisor sum of n.
###Input example:
```in
twenty
```
###Output example:
```out
eighteen
```
###Input example:
```in
twenty-eight
```
###Output example:
```out
twenty-eight
```






answer：If there is no answer, please comment