Is 6 a polynomial

Yes 6 is a polynomial, according to the Hawks Learning System.

a more detailed explanation

"A polynomial is defined as a term or a finite sum of terms, with only positive or zero integer exponents permitted on the variables" (Lial, Hornsby, Schneider; 2005)

and "The product of a real number and one or more variables raised to powers is called a term" (Lial, Hornsby, Schneider; 2005)

So since any variable raised to the zero power is 1, then 6x^0 is the same as 6x1, which equals 6.

So yes, 6 is considered a polynomial.