You can search for that, it’s quite famous.
In short: Ramanujan (Indian clerk, ‘uneducated’, but brililiant at numbers) was in the hospital and Hardy (English mathematician, quote:’ I do number theory, because that is the only part of mathematics that has no use outside of math’, or something along those lines) came to visit him and said ‘I came here in a cab with number 1729; that is such a boring number: I hope it’s not a bad omen.’
Then Ramanujan thought for a few seconds and replied: ‘On the contrary: 1729 is very interesting: it’s the smallest number that can be written in two distinct ways as the sum of two cubes’ (Namely: 9³ + 10³ and 1³ + 12³)
