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A comment on 2^74207281-1 is Prime. Parent comment

Re:2^74207281-1 is Prime by seibelj on Tuesday January 19, 2016 @12:09PM (#10932054)
No, the number 5 is prime, yet in binary it is 101. The new prime number could have many zeroes interspersed with ones, so you don't know how many 1 digits it has.

EDIT: I have realized my mistake in the representation of 2's complement. However, I will leave this here for posterity.

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Re:2^74207281-1 is Prime by gill984 on Tuesday January 19, 2016 @12:26PM (#10932190)
It's a Mersenne Prime, so it is 1 less than some power of 2. This results in all of its non-leading digits in binary being 1s.
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Re:2^74207281-1 is Prime by theandrewbailey on Tuesday January 19, 2016 @12:25PM (#10932185)
But 5 is not 2^n-1
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Re:2^74207281-1 is Prime by eggy on Tuesday January 19, 2016 @03:25PM (#10933697)
5 is a prime number true, but not a Mersenne prime number. The Mersenne prime number 31 has 5 as its exponent n [1].

[1] http://mathworld.wolfram.com/MersennePrime.html

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