Handle 20.000 users in same time

Hello everyone. My question is if i can handle 20.000 people in same time with this items:
-HP Server 2x6cores,64GBRAM
-HP Server 2x6cores,64GBRAM
I have two servers…
-Netgear 24Port Gigabit Ethernet Switch
-24Port Gigabit Ethernet managed switch

This is what i have now. What i need more to host a website (Social Network) with 20.000 visitors at once ?
Please,a short list with what you recommend me for handle all this people. Thank you!

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