869243561 has 2 divisors, whose sum is σ = 869243562. Its totient is φ = 869243560.

The previous prime is 869243549. The next prime is 869243563. The reversal of 869243561 is 165342968.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 796311961 + 72931600 = 28219^2 + 8540^2 .

It is a cyclic number.

It is not a de Polignac number, because 869243561 - 2¹⁰ = 869242537 is a prime.

Together with 869243563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (869243563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 434621780 + 434621781.

It is an arithmetic number, because the mean of its divisors is an integer number (434621781).

Almost surely, 2^869243561 is an apocalyptic number.

It is an amenable number.

869243561 is a deficient number, since it is larger than the sum of its proper divisors (1).

869243561 is an equidigital number, since it uses as much as digits as its factorization.

869243561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 311040, while the sum is 44.

The square root of 869243561 is about 29482.9367770580. The cubic root of 869243561 is about 954.3635136477.

The spelling of 869243561 in words is "eight hundred sixty-nine million, two hundred forty-three thousand, five hundred sixty-one".