This should be an easy one for the “Dopers”.
Here’s some I’ve already found:
28 is the second perfect number being the sum of its divisors: 1; 2; 4; 7; 14
28 is the sum of the first 5 prime numbers 2; 3; 5; 7; 11
There are 28 days in a non-leap-year February.
This is not a homework assignment. (It’s been decades since I’ve had a homework assignment. LOL)
Anyway, just 25 more fun-facts to go for the number 28.
Four touchdowns (with extra points.)
The moon orbits in 28 days.
A “normal” menstrual cycle is 28 days.
Whoops, quoted instead of posted…
28
The number of Reese Cup Miniatures I’ve eaten in the last 12 minutes.
[sub]Ruby, the PMS Poster Child[/sub]
28 is the square root of 784.
Both of the digits in 28 are powers of 2.
*You really miss the consecutive number thread don’t you Wolf Meister
LOL MoeJuck
As I’ve said, I had a love/hate relationship with that thread. I loved finding weird and or oddball properties for those numbers (… this is a sum of 2 triangular numbers and 3 consecutive primes…)
But as I’ve said, I sometimes would spend up to 30 minutes just to post one number. (So it is good that it is gone… but :::: sigh ::::
Anyway - another “fun fact” about 28?
In the short run, the calendar runs on a 28 year cycle. (This is due to 7 days per week and a leap day every 4 years.) Of course what messes this up is that 3 out of 4 century years cannot be Leap Years and so in the long run the calendar is actually on a 400 year cycle.
And for those of you still awake, another fun fact of 28? It is the last 2 digits of www.1728.com - not only a great website but possibly the greatest achievement in Western Civilization - the world shall never see its like again (IMHO). LOL
Geez, I thought I would have had a plethora of fun facts about 28 by now.
Okay 28 Days A Sandra Bullock movie from 2000
28 Days Later Although sounding as if its the sequel to the above movie, it is actually a sci-fi movie from 2002.
Um… it lies exactly between 27 and 29?
An NFL football has a circumference of 28 inches at its widest point, and is approximately 28 centimeters long.
If you liked that thread, you might like http://www.stetson.edu/~efriedma/numbers.html
Um… a solution for 28 in the “four 4’s” problem is
44 - 4*4
It’s 11100 in binary or 1C in hex.
It’s 2/3 of the “meaning of life” (42)
Oh, what’s that? Interesting facts? Sorry…
Geez, how did we forget this one ?
28 is a triangular number being the sum of the integers 1 through 7 !!!
Wow where’s the smack-the-head icon when you need it ?
Boy is my face red !!!
Even counting the “Peanut ButterCups” posting, we’re barely past the half-way mark. 
wait wait wait. . .
In regards to your first “fact”:
How can you have the number (1) without the number (28)??
Shouldn’t it be 1,2,4,7,14,28?? And therefore not be the sum of its divisors?
If it’s the second number with this quality, what is the first?
28 is the the first triangular number to be the sum of two cubes 1[sup]3[/sup]+3[sup]3[/sup].
The longest known sociable chain has 28 links, starting with 12,496.
Much more importantly, there are 28 dominoes in a standard double-six set.
28 is double the number of this post in this thread!
Thank you.
Bear_Nenno
I’m as unhappy about the “perfect number” definition as you are.
You don’t count 1 as a factor, You don’t count 1 as a prime number, so why on earth do “they” decide that 1 is a divisor?
Oh and the 1st perfect number is 6.
Tapioca that’s great - keep up the good work !!!
Ghanima - well thanks for your help too.
The probability of dealing a perfect hand in bridge is 1 in 2,235,197,406,895,366,368,301,560,000 - which has 28 digits.
28 is the atomic number of nickel.
Matthew and Acts are the only books of the bible with 28 chapters.
28 is the number of letters in “Numerology is just pareidolia” + 2 which is the first prime number!!!
28 is XXVIII in Roman Numerals