6531 has 8 divisors (see below), whose sum is σ = 9984. Its totient is φ = 3720.

The previous prime is 6529. The next prime is 6547. The reversal of 6531 is 1356.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 6531 - 2¹ = 6529 is a prime.

It is a super-2 number, since 2×6531² = 85307922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (15) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

6531 is a lucky number.

It is a nialpdrome in base 10.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 6531.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135 + ... + 176.

It is an arithmetic number, because the mean of its divisors is an integer number (1248).

2⁶⁵³¹ is an apocalyptic number.

6531 is a deficient number, since it is larger than the sum of its proper divisors (3453).

6531 is a wasteful number, since it uses less digits than its factorization.

6531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321.

The product of its digits is 90, while the sum is 15.

The square root of 6531 is about 80.8146026409. The cubic root of 6531 is about 18.6921774215.

Subtracting from 6531 its product of digits (90), we obtain a triangular number (6441 = T₁₁₃).

Adding to 6531 its reverse (1356), we get a palindrome (7887).

The spelling of 6531 in words is "six thousand, five hundred thirty-one".