The torus, cut open. Every integer n sits at (log₂ n, depth Ω(n)). A prime is one step of (log₂ p, 1); a composite is where a chain of steps lands. Reorder the steps (dashed) and you land on the same point.
p = 2
p = 3
p = 5
p = 7
p = 11
p = 13
p ≥ 17
other composite
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steplands onlog₂ ndepth
{{r.step}}{{r.lands}}{{r.lg}}{{r.dep}}
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The same route on the torus
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Center: the horn torus pinches shut at depth 3.5. Every helix (faint lines) crosses it whatever its φ, and no integer lands there.