# Online Calculate Sum of Proper Divisors

positive integer:

Prime Factors: {{ primes }}

Sum of Proper Divisors: {{ sum }}

Online tool for prime factorization and calculating sum of proper divisors. The following is source code of the tool. For more details of the algorithm, see [1].

HTML:

```<div id="vueapp">
positive integer: <input v-model="intn" placeholder="Input positive integer">
<p>Prime Factors: {{ primes }}</p>
<p>Sum of Proper Divisors: {{ sum }}</p>
</div>

<script src="https://cdn.jsdelivr.net/npm/vue@2.5.16/dist/vue.js"></script>
```

JavaScript:

```'use strict';

// Get all prime factors of a given number n
function PrimeFactors(n) {
if (n==1) {return [1];}

var pfs = [];
// Get the number of 2s that divide n
while (n%2 == 0) {
pfs.push(2);
n /= 2;
}

// n must be odd at this point. so we can skip one element
// (note i = i + 2)
for (var i=3; i*i <= n; i += 2) {
// while i divides n, append i and divide n
while (n%i == 0) {
pfs.push(i);
n /= i;
}
}

// This condition is to handle the case when n is a prime number
// greater than 2
if ( n>2 ) {
pfs.push(n);
}

return pfs;
}

function SumOfDivisors(pfs) {
var m = {};
for (var i = 0; i < pfs.length; i++) {
var prime = pfs[i];
if (m.hasOwnProperty(prime)) {
m[prime] += 1;
} else {
m[prime] = 1;
}
}

var sum = 1;
for (var prime in m) {
var exponents = m[prime];
sum *= (Math.pow(prime, exponents+1)-1) / (prime-1);
}
return sum;
}

new Vue({
el: '#vueapp',
data: {
intn: 284,
primes: "",
sum: ""
},
watch: {
intn: {
immediate: true,
handler(val, oldVal) {
var n = parseInt(val);
if (isNaN(n) || n<1) {
this.primes = "please input positive integer";
return;
}

var pfs = PrimeFactors(n);
this.primes = pfs;
this.sum = (SumOfDivisors(pfs) - n);
}
}
}
});
```

Tested on:

• Chromium 65.0.3325.181 on Ubuntu 17.10 (64-bit)
• Vue.js 2.5.16

References: