For the first part of the problem, the circumference does not matter. The rope must have a diameter 20 meters more than the circumference of the Earth. The circuference of a circular rope 20 meters more in diameter is 20Pi = 62.831 853 meters.

Rope = 40,000,062.831 853 meters.

Divide by 5 results in 8,000,012.566 men holding the rope. Multiply by the number or stilts per man. Looks like 16,000,025 men to me.