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Description
27 (twenty-seven) is the natural number following 26 and preceding 28. Twenty-seven is the smallest positive integer requiring four syllables to name in English, though it can be unambiguously defined in just two: "three cubed."

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Twenty-seven is a perfect cube, being 3³ = 3 × 3 × 3. 27 is therefore the second smallest cube of a prime number. 27 is 23 (see tetration). There are exactly 27 straight lines on a smooth cubic surface, which give a basis of the fundamental representation of the E6 Lie algebra. 27 is also a decagonal number.

27 has an aliquot sum of 13 and is the first composite member of the 13-aliquot tree with the aliquot sequence (27,13,1,0). Twenty-seven is the aliquot sum of the two odd discrete semiprimes 69 and 133.

In base 10, it is the first composite number not evenly divisible by any of its digits. It is the radix (base) of the septemvigesimal positional numeral system.

In a prime reciprocal magic square of the multiples of 1/7, the magic constant is 27.

In the Collatz conjecture (aka the "3n + 1 conjecture") a starting value of 27 requires 112 steps to reach 1, many more than any lower number.

The unique simple formally real Jordan algebra, the exceptional Jordan algebra of self-adjoint 3 by 3 matrices of quaternions, is 27-dimensional.[1]

In base 10, it is a Smith number and a Harshad number.

It is the twenty-eighth (and twenty-ninth) digit in π. (3.141592653589793238462643383279...)

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Wolfgang Mozart was born on January 27, 1756. He completed 27 concerti for piano and orchestra.

Many talented and famous rock/blues musicians died at age 27. These include Robert Johnson, Janis Joplin, Jimi Hendrix, Brian Jones, Jim Morrison, Ron "Pigpen" McKernan, Pete Ham, Richey Edwards, and Kurt Cobain. The musicians who died at this age are often referred to as the 27 Club.

Description
27 (twenty-seven) is the natural number following 26 and preceding 28. Twenty-seven is the smallest positive integer requiring four syllables to name in English, though it can be unambiguously defined in just two: "three cubed."

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Twenty-seven is a perfect cube, being 3³ = 3 × 3 × 3. 27 is therefore the second smallest cube of a prime number. 27 is 23 (see tetration). There are exactly 27 straight lines on a smooth cubic surface, which give a basis of the fundamental representation of the E6 Lie algebra. 27 is also a decagonal number.

27 has an aliquot sum of 13 and is the first composite member of the 13-aliquot tree with the aliquot sequence (27,13,1,0). Twenty-seven is the aliquot sum of the two odd discrete semiprimes 69 and 133.

In base 10, it is the first composite number not evenly divisible by any of its digits. It is the radix (base) of the septemvigesimal positional numeral system.

In a prime reciprocal magic square of the multiples of 1/7, the magic constant is 27.

In the Collatz conjecture (aka the "3n + 1 conjecture") a starting value of 27 requires 112 steps to reach 1, many more than any lower number.

The unique simple formally real Jordan algebra, the exceptional Jordan algebra of self-adjoint 3 by 3 matrices of quaternions, is 27-dimensional.[1]

In base 10, it is a Smith number and a Harshad number.

It is the twenty-eighth (and twenty-ninth) digit in π. (3.141592653589793238462643383279...)

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Wolfgang Mozart was born on January 27, 1756. He completed 27 concerti for piano and orchestra.

Many talented and famous rock/blues musicians died at age 27. These include Robert Johnson, Janis Joplin, Jimi Hendrix, Brian Jones, Jim Morrison, Ron "Pigpen" McKernan, Pete Ham, Richey Edwards, and Kurt Cobain. The musicians who died at this age are often referred to as the 27 Club.