61

This number is a prime.

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

61 is a prime Euler number. [Post]

Figurately speaking, 61 is both the 6th (6*1) centered square number and the 5th (6-1) centered hexagonal number. [Post]

The great Topologist John Milnor had his conjecture disproved by M. Mahowald, who found S(61), the set of all oriented diffeomorphism classes of closed smooth homotopy 61-spheres is the trivial group. Reference: "Differential Toplogy Forty-Six Years Later", John Milnor, Notice of the AMS, June/July 2011, pp.804-809. [Post]