# User:Charles Matthews/1729 (number)

1729
Cardinal One thousand seven hundred (and) twenty-nine
Ordinal One thousand seven hundred (and) twenty-ninth
Factorization ${\displaystyle 1729=7\cdot 13\cdot 19}$
Roman numeral MDCCXXIX
Binary 11011000001

1729 is an integer, most notable for being the Hardy-Ramanujan number (the smallest number expressible as the sum of two cubes in two different ways). It is also the third Carmichael number.

Numbers such as

1729 = 13+123 = 93+103

which can be expressed as the sum of cubes in n distinct ways have been dubbed taxicab numbers, written Ta(n). 1729 is thus Ta(2).

Another interesting property of the number is that the 1729th decimal place is the beginning of the first occurrence of all ten digits consecutively in the decimal representation of e.