Dodge the Mods! Counting Game!

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515.

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516.

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[h=3]517[/h]
517 = 11 x 47.


517 is the smallest number n such that n + sigma(n) + sigma(sigma(n)) is a cube, where sigma(n) is the sum of all divisors of n.


517 is the sum of five consecutive prime numbers: 517 = 97 + 101 + 103 + 107 + 109.


517 is a Smith number. A Smith number is a composite number for which, in a given base, the sum of its digits is equal to the sum of the digits in its prime factorization: 5 + 1 + 7 = 1 + 1 + 4 + 7.

517 is the telephone area code that covers Lansing, Mich., and neighboring areas.

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MU519_NASA.jpg

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520.

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521 is a prime number.


521 has a representation as a sum of two squares: 521 = 11² + 20².


521 is the 13th Lucas number.


521 and 523 for a twin prime pair.


521 is the hypotenuse of a primitive Pythagorean triple: 521² = 279² + 440².


521 has the representation 521 = 2⁹ + 9.


521 is the exponent of the Mersenne prime 2⁵²¹ - 1.


521 is the smallest prime whose reversal is a cube: 125 = 5³.



Galaxy cluster Abell 521 is located about 2.9 billion light-years from Earth.

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523_fr525s_vig.jpg

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524.