What is 2¹⁶, and why does it matter for networking?

65536 — the number of TCP/UDP ports, and the range of a 16-bit unsigned integer (0–65535).

Chunk 65536 → 65 · 53 · 6 → shell · lamb · shoe: a lamb and a shoe tucked inside a giant sea shell. Because port numbers are 16 bits, there are exactly 2¹⁶ = 65536 of them (0–65535) — which is why the highest port is 65535.

Tip: 65536 = 64 KiB, the addressable memory of many classic 8-bit and 16-bit machines.