Twenty-nine

Twenty-nine (29, XXIX) is the natural number following twenty-eight and preceding thirty. It is the tenth prime number, and also a primorial prime, the next prime number as well as primoral prime being thirty-one, with which it comprises a twin prime. Twenty-nine is also the sum of three squares, 2² + 3² + 4². It is a Lucas number and a Pell number.

The lunar month is very close to twenty-nine days.

Twenty-nine is also

• The atomic number of copper.
• The number of days February has on leap years.
• The number of letters in the Finnish and Norwegian alphabets.
• The designation of Interstate 29, a freeway that runs from Missouri to North Dakota.
• In the name of the town Twentynine Palms, California, also the name of the adjoining Marine Corps base, affectionately referred to by Marines as "Twentynine Stumps".

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See also: twenty-seven, twenty-eight, thirty, thirty-one, integer, list of numbers.

This article is about the number. For the year AD 29, see 29.