Seventy-two
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Seventy-two (72, LXXII) is a natural number following seventy-one and preceding seventy-three. It is a composite number with the divisors being 2, 3, 4, 6, 8, 9, 12, 16, 18, 24 and 36. Its factorization is:

It is the sum of four consecutive primes (13 + 17 + 19 + 23), as well as the sum of six consecutive primes (5 + 7 + 11 + 13 + 17 + 19).

In normal space, the exterior angles of an equilateral pentagon measure 72 degrees each.

Seventy-two is also:

• The atomic number of hafnium.
• The total number of books in the Holy Bible in the Catholic version if the Book of Lamentations is considered part of the Book of Jeremiah.
• The designation of USA Interstate 72, a freeway that runs from Missouri to Illinois.
• The registry of the U.S. Navy's nuclear aircraft carrier USS Abraham Lincoln (CVN-72), named after U.S. President Abraham Lincoln.
• The designation of the Soviet T-72 tank.
• The number of hours in three days.

This article is about the number. For the year AD 72, see 72.

The original article can be found at: http://en.wikipedia.org/wiki/Seventy-two.
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