21st of June.
north pole
4383 hours.
Twenty-four hours of daylight.
On a solstice, it is only at the equator that the hours of light and dark are equal. At other parts, they would be different with one of the Poles experiencing 24 hours of daylight and the other Pole experiencing no daylight. If it is the June solstice, then it is the North Pole with 24 hours of daylight and the South Pole with none, while it is the opposite in the December solstice. It is at the equinox that the amount of daylight and darkness hours are equal around the world.
24 hours
The location that has the greatest number of daylight hours in a year is the North Pole. During the summer solstice, the North Pole experiences 24 hours of continuous daylight due to the tilt of the Earth's axis.
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.
There is a very minimal amount of daylight in the North Pole. By the equator, there is much more sunlight and a much more warmer climate.
I think 24 hours
There is no single answer to that. Different parts of the northern hemisphere will have different lengths of daylight on the 21st of June. The further north of the equator you go, the more hours of daylight there will be, with there being about 12 hours at the equator and 24 hours at the north pole. So you need to know exactly where in the northern hemisphere you are before the question can be answered.
On June 21, the summer solstice, locations between 66.5 degrees North (the Arctic Circle) and 90 degrees North (the North Pole) experience 24 hours of daylight. This phenomenon occurs because the North Pole is tilted towards the Sun during this time, resulting in continuous sunlight for regions within the Arctic Circle. As you move closer to the Pole, the duration of daylight remains constant at 24 hours.
June 21, North Pole: Bright sun 24 hours, snow everywhere, but feels warm or cool. June 21, Equator: 12 hours day, hot and steamy; 12 hours night, hot and steamy. December 21, North Pole: Night 24 hours, snow everywhere, feels very cold, sometimes a bright moon and aurora. December 21, Equator: 12 hours day, hot and steamy; 12 hours night, hot and steamy.