531661 has 4 divisors (see below), whose sum is σ = 572572. Its totient is φ = 490752.

The previous prime is 531637. The next prime is 531667. The reversal of 531661 is 166135.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 275625 + 256036 = 525^2 + 506^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-531661 is a prime.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (531667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20436 + ... + 20461.

It is an arithmetic number, because the mean of its divisors is an integer number (143143).

2⁵³¹⁶⁶¹ is an apocalyptic number.

It is an amenable number.

531661 is a deficient number, since it is larger than the sum of its proper divisors (40911).

531661 is a wasteful number, since it uses less digits than its factorization.

531661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40910.

The product of its digits is 540, while the sum is 22.

The square root of 531661 is about 729.1508760195. The cubic root of 531661 is about 81.0111756160.

Adding to 531661 its reverse (166135), we get a palindrome (697796).

The spelling of 531661 in words is "five hundred thirty-one thousand, six hundred sixty-one".