Caveat - I am NOT an electrician. Use common sense and caution. Hire an electrician if you don't know what you are doing.
Nowadays, most new homes have multiple 20 Amp appliance circuits in the kitchen at the countertop level. As the previous poster stated, a true 20 Amp plug will have a straight up and down slot (|) and a tee-shaped slot (|-), or possibly even just a (-) for a dedicated 20 Amp circuit (I may be wrong here).
You need three things... the appropriate outlet, the proper gauge (likely 12AWG, not 14AWG) wiring internal to your walls (and a reasonable length to the circuit breaker) and a 20A breaker installed in the circuit panel for that particular circuit.
I would first check the circuit breaker for the outlet in question in your Circuit Breaker panel box. It should be marked 20A.
Once you have found the circuit, see what other outlets are affected. If another high draw device like a toaster, blender or microwave are on the same circuit, you will need to takes steps to avoid the use of both at the same time. Better yet, relocate the other devices and or disable the other outlets if possible.
With the circuit off, remove the outlet cover and receptacle and check to see if you the wiring is 12AWG or better (meaning a lower number here, 10AWG is better than 12AWG). The wire is usually printed with the AWG rating on the wire insulation).
If you don't have a 20A rated receptacle (google NEMA 5-20, available at all home centers), you'll need to change the outlet receptacle.