RFC1918  (IPv4) 20-bit block private address space

For 172.16.0.0/12 network 
netmask 255.240.0.0  binary 11111111 11110000 00000000 00000000  

Base address
172.16.0.0  binary 10101100  00010000  00000000  00000000

Highest address
172.31.255.255  binary 10101100 00011111 11111111 11111111

Number of IPv4 addresses in this private block is 1,048,576