Mathematics · Algebra
Sum of Divisors Calculator
Add every positive divisor of a whole number.
Inputs and results stay in this browser. Change one value at a time to explore the relationship.
Calculation steps
- Apply the prime-power geometric-series formula to 12.
- σ(12)=28; proper sum=16.
Problem → model → reason → result
What problem does this model solve?
Add every positive divisor of a whole number.
Why does the model apply?
Each prime contributes a finite geometric series of allowed powers.
What assumptions does it make?
The entered values are real numbers, the stated equation or relationship represents the problem, and no excluded value makes a denominator zero or an operation undefined.
Formula
σ(n)=∏(p^(a+1)−1)/(p−1)
Calculation and working
The calculator above substitutes your inputs into the model and leaves the calculation steps visible so the answer can be checked rather than merely accepted.
What does the result mean?
The result answers the stated problem in the units implied by your inputs. Read its sign, size and units together, then compare it with the original values before drawing a conclusion.
Worked example
The divisors of 12 sum to 1+2+3+4+6+12=28.
Common mistake
This includes n itself; proper-divisor sums exclude it.
When does this model not apply?
The result solves the displayed mathematical form; it cannot determine whether that form is the correct model for an unstated real-world problem.
How to learn with this calculator
Begin with the worked example, then change one value while keeping the others fixed. Compare the new result and calculation steps to identify which part of the formula changed.
Clear answers
Frequently asked questions
What does the Sum of divisors do?
Add every positive divisor of a whole number.
How does the Sum of divisors work?
The calculator applies σ(n)=∏(p^(a+1)−1)/(p−1). Each prime contributes a finite geometric series of allowed powers.
What can I learn from the Sum of divisors?
It connects the mathematical rule to your chosen numbers and shows each calculation step. Change one input at a time to see how the result responds.
Does MW SysArc receive or store what I enter?
No. The calculation runs locally in your browser. MW SysArc does not receive or store your calculation inputs.
How should I use the result?
Use the steps to understand the method, then verify important school or professional work using the notation and rounding rules required in your setting.
Last reviewed 2026-07-14. Calculations tested 2026-07-14.