531 = 32 x 59.
531 is the smallest number with the property that its first four multiples contain the digit 1: 531, 1062, 1593, and 2124.
291,548,736 = 8 x 92 x 531 x 746. Both the number and its factors use each of the digits from 1 to 9 exactly once.
531 is 20103 in base 4 and 213 in base 16.
The construction of the St. Sophia Basilica in Constantinople began in the year 531.
