An exponential function is a function in which the variable is in the exponent.
Functions of the type :

Here the exponent is an integer.
Such functions are called Arithmetic functions.
Functions of the type
y = 2 ^x
Here the exponent of 2 is a variable.
Such functions are called exponential functions
We are given y =6 x^7.
Here the variable is base & the exponent is an integer.
So does not represent an exponential function.