Question 814037
<pre>
19845k = 3*3*3*3*5*7*7k = 3<sup>4</sup>*5<sup>1</sup>*7<sup>2</sup>k

by a value that will make it
a perfect cube, we much choose a value that will cause
every factor to have an exponent which is a multiple of 3.

The 3<sup>4</sup> must be multiplied by 3<sup>2</sup> so it
will become 3<sup>6</sup> 

The 5<sup>1</sup> must be multiplied by 5<sup>2</sup> so it
will become 5<sup>3</sup>

The 7<sup>2</sup> must be multiplied by 7<sup>1</sup> so it
will become 7<sup>3</sup>


So we must multiply 3<sup>4</sup>*5<sup>1</sup>*7<sup>2</sup> by
3<sup>2</sup>*5<sup>2</sup>*7<sup>1</sup>

So k = 3<sup>2</sup>*5<sup>2</sup>*7<sup>1</sup> = 9*25*7 = 1575

So the smallest possible positive integer value of k is 1575

Checking:

19845*1575 = 31255875 = 315³ 

Edwin</pre>