Analog watch simulation
Don't repeat yourself

The step of drawing the hour, minute, second hands are all very similar.
It would be good to use a helper function:

public void Draw(SpriteBatch spriteBatch, Texture2D hand, int value, Vector2 vector2, float coef)
{
    spriteBatch.Draw(hand, center, null, null, vector2,
        value * Math.PI * coef,
        null, Color.White, SpriteEffects.None, 0);
}


Visibility

Since the hour, minutes, seconds should not be visible outside the class,
it would be good to make them explicitly private.
(Thanks @Maxim for the clarification that the default access modifier is actually private.)