It would take about 42 h.
This involves several assumptions. Here are mine:
- The mass of a bacterium is 1 × 10⁻¹⁵ kg.
- The mass of a human is 70 kg.
- There is only exponential growth, with no lag phase or stationary phase.
The equation for exponential growth is
64.9 min × 38.8 h = 2520 min = 42 h (2 significant figures)