Total number of factors of N = (p + 1)(q + 1)(r + 1)(s + 1).
Sum of all factors of N
i) The product of factors of a composite number N = , where 'n' is
the total number
of factors of N.
ii) Let N = p1a × p2b
× p3c × . . . × ex, where p1,
p2, p3, . . . are the odd prime factors and 'e' is the even prime
number. The total number of odd factors of N = (a + 1)(b + 1)(c + 1) . . .
In order to
find the total number of even factors of N, we simply subtract the total number of odd
factors of N from the total number of factors of N.
iii) The number of ways of expressing a composite number as a product of
two factors × total
number of factors.