Well, the Hijri date 21 Rabi Al Thani 1405 corresponds to the Gregorian date Saturday, 12 January 1985. This date lies in the fourth month of the Hijri year 1405 AH, which is Rabi Al-Thani of 1405 AH. Both this Hijri and Gregorian date occur on the single day that is Saturday without any doubt. The Arabic date 1405/04/21 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 12 January 1985 to its equivalent Arabic date.
The following is the conversion of the Arabic date 21 Rabi Al Thani 1405 AH to its equivalent Gregorian date.
فَبِمَا نَقْضِهِم مِّيثَٰقَهُمْ وَكُفْرِهِم بِـَٔايَٰتِ ٱللَّهِ وَقَتْلِهِمُ ٱلْأَنۢبِيَآءَ بِغَيْرِ حَقٍّۢ وَقَوْلِهِمْ قُلُوبُنَا غُلْفٌۢ ۚ بَلْ طَبَعَ ٱللَّهُ عَلَيْهَا بِكُفْرِهِمْ فَلَا يُؤْمِنُونَ إِلَّا قَلِيلًۭا
Then because of their breaking of their covenant, and their disbelieving in the revelations of Allah, and their slaying of the prophets wrongfully, and their saying: Our hearts are hardened - Nay, but Allah set a seal upon them for their disbelief, so that they believe not save a few -
Surah An-Nisaa(4:155)