IMO GiB and gigabit are deliberately consumer-confusing terms with an even clearer standard definition.
• 480p/480i, SD
• 720p/720i, HD
• 1080p/1080i, full HD, 2K*
• 2160p, ultra HD, 4K*
* actually refers to several resolutions with different aspect ratios, but roughly the same pixel count
But definitely there is nothing 4000 about it, it's 3840 by 2160, about 8.3 megapixels.