How this factor calculator works
Enter a positive whole number. The page lists every positive factor, the divisors that split it with no remainder, and counts them. For 12 the factors are 1, 2, 3, 4, 6, 12, so the total is 6.
Factors come in pairs that multiply back to the number. The search runs from 1 up to the square root. Each time a divisor fits evenly, both that divisor and its pair are saved, then the list is sorted from smallest to largest. For 28 the pairs are 1 × 28, 2 × 14, and 4 × 7, so the line reads 1, 2, 4, 7, 14, 28.
A perfect square pairs its square root with itself, and that root is written once. 36 includes 6 a single time, because 6 × 6 = 36, and the total is 9: 1, 2, 3, 4, 6, 9, 12, 18, 36. 49 is 1, 7, 49. An ordinary number has an even count. A prime has exactly two factors, 1 and itself. 7 is 1, 7. The number 1 has only one factor, so it is not prime.
This is the full list of positive divisors, not a prime factorization. Prime factorization of 12 is 2 × 2 × 3. The factor list also includes 4 and 6. Only positive factors are shown. 0, negative numbers, and decimals are rejected, and the result stays -- until the box holds a positive integer.