On the relation between the digital sum and product of a natural number
Laurenţiu Panaitopol · Publikacija Elektrotehnickog fakulteta - serija matematika · 2004
For an integer n ≥ 1 one denotes by sb(n) the sum of its digits and by pb(n) the product of its digits with respect to the basis b. In the present paper one compares sb(n) and pb(n) in the general case, as well as in several special cases, e.g., when n has a given number of digits or when n is the square of a natural number.