531 has 6 divisors (see below), whose sum is σ = 780. Its totient is φ = 348.

The previous prime is 523. The next prime is 541. The reversal of 531 is 135.

Added to its reverse (135) it gives a triangular number (666 = T₃₆).

531 is nontrivially palindromic in base 12.

It is not a de Polignac number, because 531 - 2³ = 523 is a prime.

It is a super-2 number, since 2×531² = 563922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 59 = 531 / (5 + 3 + 1).

531 is an undulating number in base 12.

It is a straight-line number, since its digits are in arithmetic progression.

It is a plaindrome in base 7, base 14 and base 15.

It is a nialpdrome in base 5, base 9, base 10 and base 11.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 531.

It is not an unprimeable number, because it can be changed into a prime (521) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 21 + ... + 38.

It is an arithmetic number, because the mean of its divisors is an integer number (130).

531 is a deficient number, since it is larger than the sum of its proper divisors (249).

531 is a wasteful number, since it uses less digits than its factorization.

531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65 (or 62 counting only the distinct ones).

The product of its digits is 15, while the sum is 9.

The square root of 531 is about 23.0434372436. The cubic root of 531 is about 8.0977588679.

Adding to 531 its reverse (135), we get a palindrome (666).

It can be divided in two parts, 5 and 31, that added together give a triangular number (36 = T₈).

The spelling of 531 in words is "five hundred thirty-one", and thus it is an aban number.