Date formatting in GAWK: boot time

I have one server with apparently an exceptional stability:
# uptime

3:45pm  up 524 days,  1:22,  1 user,  load average: 0.44, 0.16, 0.13

Unfortunately I know this is not correct (I remember rebooting it some weeks ago). So what are other ways to get the date/time of the last boot?

Looking at the RedHat manuals, the following thing should work too:
# cat /proc/stat
cpu 33813143 210619911 30093342 59435750
cpu0 33813143 210619911 30093342 59435749
(...)
btime 1096157569
(...)

The btime gives us the last boot time in seconds since 1 Jan 1970. I can find and convert it with gawk:
# gawk "/btime/{ print (`date +%s` - $2) / (3600 * 24.0) ,"days -",strftime("%a %b %d %H:%M:%S %Z %Y",$2)}" /proc/stat
38.6473 days - Sun Sep 26 02:12:49 CEST 2004

Which gives us an uptime of 38,6 days – that looks more like it!

Another way of calculating the uptime:
# gawk "/cpu/ {print $1,($2 + $3 + $4 + $5)/(3600 * 24 * 100)}" /proc/stat
cpu 38.6515
cpu0 38.6515

Confirmation of the previous measurement!

# cat /proc/uptime
45282758.17 663091.26

The first number is the # of seconds since last boot. The other one (idle time) we don’t need. What is that in days?
# gawk "{print $1/(3600 * 24.0)}" /proc/uptime
524.106

This is where the wrong data is coming from! So I’ll ignore this data.

Remark: This server is one of my oldest ones and is still running Redhat 7.2 (Enigma). Looks like this bug was fixed in later versions of RedHat, since none of my other servers have it.

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