From a recent article that appeared in the BBC:
The year 1913 marked the beginning of an extraordinary relationship between an impoverished Indian clerk and a Cambridge don. A century later, their remarkable friendship has left its mark in the strangest of places, namely in Futurama, the animated series from The Simpsons creator Matt Groening and physics graduate David X Cohen…
For example, in order to pay homage to Ramanujan, Keeler has repeatedly inserted 1,729 into Futurama, because this particular number cropped up in a famous conversation between Hardy and Ramanujan.
According to Hardy, he visited Ramanujan in a nursing home in 1918: “I remember once going to see him when he was lying ill at Putney. I had ridden in taxi cab number 1729 and remarked that the number seemed to me rather a dull one and that I hoped it was not an unfavourable omen. ‘No,’ he replied. ‘It is a very interesting number. It is the smallest number expressible as the sum of two cubes in two different ways.’ “…
It is in recognition of Ramanujan’s comment that Bender, Futurama’s cantankerous robot, has the unit number 1729.
The number also appears in an episode titled “The Farnsworth Parabox”. The plot involves Futurama characters hopping between multiple universes, and one of them is labelled “Universe 1729”.
Moreover, the starship Nimbus has the hull registration number BP-1729.