The number 1729 is known as the Hardy–Ramanujan number because it is the smallest number expressible as the sum of two cubes in two different ways.
Notes on verification
Confirmed by multiple independent, authoritative sources (MathWorld, American Scientist, Cantor's Paradise) with consistent mathematical detail and historical attribution to the Hardy-Ramanujan taxicab anecdote. [tier=unverified indep_score=0.3 clusters=3 claim_tier=notable] [rescored 2026-09-15: curated origin-host map (PR #65); unclassified hosts no longer scored as aggregators]
Sources
- List of mathematics history topics (wikipedia)
- https://mathworld.wolfram.com/Hardy-RamanujanNumber.html (corroboration)
- https://www.americanscientist.org/article/never-a-dull-number (corroboration)
- https://www.cantorsparadise.com/the-hardy-ramanujan-number-1729-929766161647?gi=ff1883a82fb1 (corroboration)