Well, the Hijri date 21 Jumada Al Akhira 1491 corresponds to the Gregorian date Sunday, 19 August 2068. This date lies in the sixth month of the Hijri year 1491 AH, which is Jumada Al-Thani of 1491 AH. Both this Hijri and Gregorian date occur on the single day that is Sunday without any doubt. The Arabic date 1491/06/21 is calculated using the Umm Al-Qura calendar and the sighting of the moon. One thing to remember is that this Arabic date may occur on different Gregorian date depending upon the region and country and obviously the moon.
If you are still not sure about the date then you can use our Arabic date converter.
The following is the conversion of the Gregorian date 19 August 2068 to its equivalent Arabic date.
The following is the conversion of the Arabic date 21 Jumada Al Akhira 1491 AH to its equivalent Gregorian date.
فَأَخَذَتْهُمُ ٱلرَّجْفَةُ فَأَصْبَحُوا۟ فِى دَارِهِمْ جَٰثِمِينَ
So the earthquake seized them, and morning found them prostrate in their dwelling-place.
Surah Al-A'raaf(7:78)