531865561 has 2 divisors, whose sum is σ = 531865562. Its totient is φ = 531865560.

The previous prime is 531865511. The next prime is 531865619. The reversal of 531865561 is 165568135.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 521848336 + 10017225 = 22844^2 + 3165^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-531865561 is a prime.

It is not a weakly prime, because it can be changed into another prime (531865511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 265932780 + 265932781.

It is an arithmetic number, because the mean of its divisors is an integer number (265932781).

Almost surely, 2^531865561 is an apocalyptic number.

It is an amenable number.

531865561 is a deficient number, since it is larger than the sum of its proper divisors (1).

531865561 is an equidigital number, since it uses as much as digits as its factorization.

531865561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108000, while the sum is 40.

The square root of 531865561 is about 23062.2106702718. The cubic root of 531865561 is about 810.2156419202.

The spelling of 531865561 in words is "five hundred thirty-one million, eight hundred sixty-five thousand, five hundred sixty-one".