note
nefertari
<p>You can stop at <code>sqrt($input)</code>.</p>
<p>Example:<br/>
The divisors of 100 are:<br/>
1, 2, 4, 5, 10, 20, 25, 50, 100. They come in pairs as follows:<br/>
<code>1*100 = 100
2*50 = 100
4* 25= 100
5*20 = 100
10*10 =100
20*5= 100</code>
and so on. So at 10 which is <code>sqrt(10)</code> you are at the point where the second factor is smaller than the first and you have already tested for this pair.</p>
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