Number

1,729

1729 — The Hardy-Ramanujan Number

1,729 is a composite number, odd, a calendar year.

1729 is the famous taxicab number, the smallest number expressible as the sum of two positive cubes in two different ways:

\(1729 = 1^3 + 12^3 = 9^3 + 10^3\)

The story comes from G. H. Hardy visiting the ailing Ramanujan in hospital. Hardy remarked that he had arrived in cab number 1729, which seemed rather a dull number. Ramanujan immediately replied that, on the contrary, it was a very interesting number — the smallest expressible as the sum of two cubes in two different ways.

Sources https://en.wikipedia.org/wiki/1729_(number)

Carmichael Number Curated Deficient Number Harshad / Niven Sphenic Number Squarefree

Properties

Parity: Odd
Digit count: 4
Digit sum: 19
Digital root: 1
Palindrome: No
Divisor count: 8
σ(n) — sum of divisors: 2,240

Primality

Prime factorization: 7 × 13 × 19

Divisors & multiples

All divisors (8)

1 · 7 · 13 · 19 · 91 · 133 · 247 · 1729

Aliquot sum (sum of proper divisors): 511

Factor pairs (a × b = 1,729)

1 × 1729

7 × 247

13 × 133

19 × 91

First multiples

1,729 · 3,458 · 5,187 · 6,916 · 8,645 · 10,374 · 12,103 · 13,832 · 15,561 · 17,290

Representations

In words: one thousand seven hundred twenty-nine
Ordinal: 1729th
Roman numeral: MDCCXXIX
Binary: 11011000001
Octal: 3301
Hexadecimal: 6C1

Also seen as

Unicode codepoint

U+06C1

Other letter (Lo)

UTF-8 encoding: DB 81 (2 bytes).

Lookup U+06C1 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0006C1

RGB(0, 6, 193)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.6.193.