To see the number of CPU in Linux server

lscpu - command will display the configuration of the current linux system

$ lscpu

Also if you want only the CPU and core list, you can run below command

$ lscpu | egrep '^Thread|^Core|^Socket|^CPU\('

It will display output like below

CPU(s):                8
Thread(s) per core:    2
Core(s) per socket:    4
Socket(s):             1