Is age nothing but a number????

Just curious to know if the old saying  age ain't nothing but a number is true or not. I have this guy that 20 yrs old, who's been trying to convince me to let him take me out on a date. I am very hesitant to go on a date with him because I am 27 yrs old. So I am just curious to know whether or not i should let the age difference bother me from allowing him to take me on a date?? I never dated or talked to someone younger then me. Any advice is welcome here on this thread please and thank you.