257681 has 4 divisors (see below), whose sum is σ = 259392. Its totient is φ = 255972.

The previous prime is 257671. The next prime is 257687. The reversal of 257681 is 186752.

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 a de Polignac number, because none of the positive numbers 2^k-257681 is a prime.

It is a super-2 number, since 2×257681² = 132798995522, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (257687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 605 + ... + 938.

It is an arithmetic number, because the mean of its divisors is an integer number (64848).

2²⁵⁷⁶⁸¹ is an apocalyptic number.

It is an amenable number.

257681 is a deficient number, since it is larger than the sum of its proper divisors (1711).

257681 is a wasteful number, since it uses less digits than its factorization.

257681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1710.

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

The square root of 257681 is about 507.6228915248. The cubic root of 257681 is about 63.6347192525.

The spelling of 257681 in words is "two hundred fifty-seven thousand, six hundred eighty-one".