It is 5km to the top, which takes around 10 hours on foot. If you choose to walk it all, plan for a full day up and a full day down. Monasteries along the way offer reasonably-priced lodging, and there are several comfortable lodges on the summit. Remeber to dress in layers - a 20°C temperature variance between base and summit is normal.
A full day's hike to the summit is an unforgettable experience undertaken by many, but minibuses and cable cars are faster alternatives for travelers short on time. Some spend the night to see the sunrise, others quickly turn around and head back.