27531 is a member of OEIS A269344: magic sums of 3 X 3 semi-magic squares composed of squares of primes. See blog post Prime Squared Semi-Magic Squares.

27531 has the property that it has no repeating digits and its arithmetic and multiplicative digital roots are different from each other and from any of the digits of the number. All permutations of 12357 will have this property. See Bespoken for Sequences entry.

27531 is a number whose sum of prime factors (taken with multiplicity) is a number whose digits are identical, here 55. See Bespoken for Sequencs entry.

27531 is a lucky number.

27531 can be rendered as a digit equation as follows:

2 + 7 = 5 + 3 + 1