Well, the Hijri date 21 Shawwal 1406 corresponds to the Gregorian date Saturday, 28 June 1986. This date lies in the tenth month of the Hijri year 1406 AH, which is Shawwal of 1406 AH. Both this Hijri and Gregorian date occur on the single day that is Saturday without any doubt. The Arabic date 1406/10/21 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 28 June 1986 to its equivalent Arabic date.
The following is the conversion of the Arabic date 21 Shawwal 1406 AH to its equivalent Gregorian date.
أَيَّامًۭا مَّعْدُودَٰتٍۢ ۚ فَمَن كَانَ مِنكُم مَّرِيضًا أَوْ عَلَىٰ سَفَرٍۢ فَعِدَّةٌۭ مِّنْ أَيَّامٍ أُخَرَ ۚ وَعَلَى ٱلَّذِينَ يُطِيقُونَهُۥ فِدْيَةٌۭ طَعَامُ مِسْكِينٍۢ ۖ فَمَن تَطَوَّعَ خَيْرًۭا فَهُوَ خَيْرٌۭ لَّهُۥ ۚ وَأَن تَصُومُوا۟ خَيْرٌۭ لَّكُمْ ۖ إِن كُنتُمْ تَعْلَمُونَ
(Fast) a certain number of days; and (for) him who is sick among you, or on a journey, (the same) number of other days; and for those who can afford it there is a ransom: the feeding of a man in need - but whoso doeth good of his own accord, it is better for him: and that ye fast is better for you if ye did but know -
Surah Al-Baqara(2:184)