27
Cardinal	twenty-seven
Ordinal	twenty-seventh
Factorization
Roman numeral	XXVII
Binary	11011
Hexadecimal	1B

Twenty-seven is a perfect cube, being 3³ = 3 × 3 × 3. It is the magic result of a prime reciprocal magic square of the multiples of 1/7.

A 10,000-day-old person is 27 years old (and some months).

Twenty-seven is also:

• The atomic number of cobalt.
• The total number of books in the New Testament of the Holy Bible.
• The number of letters in the Spanish alphabet
• The current number of Amendments to the United States Constitution.
• The age in years at which rock music stars Jim Morrison, Jimi Hendrix and Kurt Cobain died.
• The code for international direct-dialed phone calls to South Africa.
• The year AD 27.