Math Is Fun Forum

I want to know , what's the math name about such a special numbers:
A natural number, N, that can be written as the sum and product of a given set of at least two natural numbers, {a1, a2, ... , ak} is called a product-sum number: N = a1 + a2 + ... + ak = a1 a2 ... ak.

For example, 6 = 1 + 2 + 3 = 1 2 3.

is there any website solve this number like pi=3.1415.......and what 's its name? (like: An "NSW number"  (named after Newman, Shanks, and Williams) is an integer m that solves the Diophantine equation 2n^2==m^2+1)

any assistance will be appreciated!