[ale] Bash script help

[Doctor Who]

I'm trying to return the value of when the last time the root password
was changed.  The script would do something like:

1) more /etc/shadow | grep root | awk -F: '{print $3}'
2) Take above value and add 1
3) Multiple the result by 86400
4) Substitute the value above after the @ below
5) date -d @XXXX +"%B %d %G"
6) Give me the output value of this

I would like to keep this done using bash.  Any help appreciated.