24 of them.
The sun sets at the South Pole about March 21 and does not rise again until about September 21. This means that on 21 June, there is no sunrise -- or 24 hours of darkness on that date.
24 hours
Twenty four hours is the length of any day on Earth.
Longest day (midsummer): 17 hours on June 21Shortest day (midwinter): 7 hours on Dec 21
543070mins
Mid-winter's Day in most of Antarctica, June 21, is a day without a sunrise. This is also true at the South Pole.
June 21
It depends on your location on Earth. At the south pole, there are 0 hours of daylight on June 21... until ~13,000 years from now when the Earth's axis of rotation will precess to give it summer in June.
It all depends on the time of year. If you're right exactly on the Arctic Circle, then: -- December 21: sun is down exactly 24 hours -- March 21: sun is up 12 hours, down 12 hours -- June 21: sun is up exactly 24 hours -- September 21: sun is up 12 hours, down 12 hours -- December 21: sun is down exactly 24 hours
June has 30*24 hours, or 720 hours
June 21 is known as the summer equinox and is the start of longer days in the Northern hemisphere. The area's closest to the equator like Equator and Hawaii are most likely to see 12 hours of both night and day on June 21.