89

This number is a prime.

Just showing those entries submitted by 'Capelle': (Click here to show all)

Photo credit: Marsha Greer
+ The largest positive integer that cannot be expressed as the sum of four pentagonal numbers. Its rightmost digit is the smallest positive integer with this property. [Capelle]

+ The largest known prime p with the property that when writing down all the natural numbers from 0 to p one uses the same number of even and odd digits. [Capelle]

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