dpkg -l | grep linux-image
hi  linux-image-4.4.0-21-generic          4.4.0-21.37                                         amd64        Linux kernel image for version 4.4.0 on 64 bit x86 SMP
hi  linux-image-extra-4.4.0-21-generic    4.4.0-21.37                                         amd64        Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
hi  linux-image-generic                   4.4.0.21.22                                         amd64        Generic Linux kernel image