Count number of CPU's in server

Run lscpu command
#lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                16
On-line CPU(s) list:   0-15
Thread(s) per core:    2
Core(s) per socket:    4
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 26
Stepping:              5
CPU MHz:               1596.000
BogoMIPS:              5866.71
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              8192K
NUMA node0 CPU(s):     0-3,8-11
NUMA node1 CPU(s):     4-7,12-15

You will get the below details

2 socket
1 soket 4 cores
2 socket means 8 cores  and 2 thread in each core

2 (Thread) * 4(core)  = 8
8 * 2(Socket)  =   16 CPU
Now also run cat /proc/cpuinfo command