257811641861 has 2 divisors, whose sum is σ = 257811641862. Its totient is φ = 257811641860.

The previous prime is 257811641833. The next prime is 257811641909. The reversal of 257811641861 is 168146118752.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 144851792836 + 112959849025 = 380594^2 + 336095^2 .

It is a cyclic number.

It is not a de Polignac number, because 257811641861 - 2¹⁰ = 257811640837 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257811671861) 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 as a sum of consecutive naturals, namely, 128905820930 + 128905820931.

It is an arithmetic number, because the mean of its divisors is an integer number (128905820931).

Almost surely, 2^257811641861 is an apocalyptic number.

It is an amenable number.

257811641861 is a deficient number, since it is larger than the sum of its proper divisors (1).

257811641861 is an equidigital number, since it uses as much as digits as its factorization.

257811641861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 645120, while the sum is 50.

The spelling of 257811641861 in words is "two hundred fifty-seven billion, eight hundred eleven million, six hundred forty-one thousand, eight hundred sixty-one".