257305 has 4 divisors (see below), whose sum is σ = 308772. Its totient is φ = 205840.

The previous prime is 257297. The next prime is 257311. The reversal of 257305 is 503752.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 100489 + 156816 = 317^2 + 396^2 .

It is not a de Polignac number, because 257305 - 2³ = 257297 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

257305 is a lucky number.

It is a plaindrome in base 14.

It is a nialpdrome in base 8.

It is an unprimeable number.

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, 25726 + ... + 25735.

It is an arithmetic number, because the mean of its divisors is an integer number (77193).

2²⁵⁷³⁰⁵ is an apocalyptic number.

It is an amenable number.

257305 is a deficient number, since it is larger than the sum of its proper divisors (51467).

257305 is an equidigital number, since it uses as much as digits as its factorization.

257305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51466.

The product of its (nonzero) digits is 1050, while the sum is 22.

The square root of 257305 is about 507.2524026557. The cubic root of 257305 is about 63.6037529265.

The spelling of 257305 in words is "two hundred fifty-seven thousand, three hundred five".