I place the veracity of such powers in their results.
Back up a sentence or two my heathen Carmel brother. Verse 17 "If he refuses to listen to them, tell the church, then treat him as you would a gentile or tax collector. Amen, I say to you, whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven."
Clearly, your pagan demand in the veracity of the fruit of prayer in verses 19 & 20, let alone your disbeleif of the Apostles miracles leads me to conclude you are merely rattling my cage, so to speak. In denying the Apostles God given miracles, you deny they were in fact gifts from Jesus.
Now I would love to exegete text with you all night, but with you as a gentile, well you know...
You deny the fact God hears and reacts to our prayers, you deny that evil roams the earth for hosts, you deny the Apostles miracles AND the resurrection of Christ himself. YOU ARE ENTITLED to that - however, if it causes no harm -just give me your first name so we can pray for YOU.