531440821 has 4 divisors (see below), whose sum is σ = 538168000. Its totient is φ = 524713644.

The previous prime is 531440807. The next prime is 531440839. The reversal of 531440821 is 128044135.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 531440821 - 2⁹ = 531440309 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 531440821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (531440321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3363471 + ... + 3363628.

It is an arithmetic number, because the mean of its divisors is an integer number (134542000).

Almost surely, 2^531440821 is an apocalyptic number.

It is an amenable number.

531440821 is a deficient number, since it is larger than the sum of its proper divisors (6727179).

531440821 is an equidigital number, since it uses as much as digits as its factorization.

531440821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6727178.

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 531440821 is about 23053.0002602698. Note that the first 3 decimals coincide. The cubic root of 531440821 is about 809.9999090586. Note that the first 4 decimals are identical.

Adding to 531440821 its reverse (128044135), we get a palindrome (659484956).

The spelling of 531440821 in words is "five hundred thirty-one million, four hundred forty thousand, eight hundred twenty-one".