257861 has 2 divisors, whose sum is σ = 257862. Its totient is φ = 257860.

The previous prime is 257857. The next prime is 257863. The reversal of 257861 is 168752.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164836 + 93025 = 406^2 + 305^2 .

It is a cyclic number.

It is not a de Polignac number, because 257861 - 2² = 257857 is a prime.

Together with 257863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 257861.

It is not a weakly prime, because it can be changed into another prime (257863) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128930 + 128931.

It is an arithmetic number, because the mean of its divisors is an integer number (128931).

2²⁵⁷⁸⁶¹ is an apocalyptic number.

It is an amenable number.

257861 is a deficient number, since it is larger than the sum of its proper divisors (1).

257861 is an equidigital number, since it uses as much as digits as its factorization.

257861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3360, while the sum is 29.

The square root of 257861 is about 507.8001575423. The cubic root of 257861 is about 63.6495328960.

The spelling of 257861 in words is "two hundred fifty-seven thousand, eight hundred sixty-one".