Ramanujan, the world famous indian mathematician didn't have any close friends. He said, "Ideal friends should be like numbers 220 and 284!".
The listeners confused and asked"what is the connection between friendship and these numbers"?
Ramanujan asked them to find out the divisors of each number. They derived and listed them as,
220-1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220

284-1, 2, 4, 71, 142, 284

Ramanujan asked them to exclude the numbers 220 and 284 and find the sum.

220-1+2+4+5+10+11+20+22+44+55+110=284

284-1+2+4+71+142=220

He explained that an ideal friendship should be like these numbers, to complement each other.
Hats off to this great idea.
Ramanujan the real genius