The kernel version is closely tight with the operating system release. To know the Solaris version/update you are using, have a look at the /etc/release file.
Any given update comes with its kernel version which might have been patched or not. 147440-13 is the patch level of your kernel. 147440-13 is recent as it was released a month ago. However, the last SunOS 10 kernel patch is 147440-15, released this week.
To get Solaris patches, use
MOS.