257645 has 6 divisors (see below), whose sum is σ = 310542. Its totient is φ = 205208.

The previous prime is 257639. The next prime is 257657. The reversal of 257645 is 546752.

257645 is nontrivially palindromic in base 15.

It can be written as a sum of positive squares in only one way, i.e., 206116 + 51529 = 454^2 + 227^2 .

It is not a de Polignac number, because 257645 - 2¹⁴ = 241261 is a prime.

It is a super-3 number, since 3×257645³ = 51308156515833375, which contains 333 as substring.

It is a Duffinian number.

257645 is an undulating number in base 15.

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 257645.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1022 + ... + 1248.

It is an arithmetic number, because the mean of its divisors is an integer number (51757).

2²⁵⁷⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

257645 is a deficient number, since it is larger than the sum of its proper divisors (52897).

257645 is an frugal number, since it uses more digits than its factorization.

257645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459 (or 232 counting only the distinct ones).

The product of its digits is 8400, while the sum is 29.

The square root of 257645 is about 507.5874308925. The cubic root of 257645 is about 63.6317556960.

The spelling of 257645 in words is "two hundred fifty-seven thousand, six hundred forty-five".