Monday, August 1, 2011

521

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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