257643 has 6 divisors (see below), whose sum is σ = 372164. Its totient is φ = 171756.

The previous prime is 257639. The next prime is 257657. The reversal of 257643 is 346752.

It is a happy number.

It is not a de Polignac number, because 257643 - 2² = 257639 is a prime.

It is a d-powerful number, because it can be written as 2 + 5⁷ + 6⁴ + 7² + 4⁵ + 3¹¹ .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257443) by changing a digit.

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, 14305 + ... + 14322.

2²⁵⁷⁶⁴³ is an apocalyptic number.

257643 is a deficient number, since it is larger than the sum of its proper divisors (114521).

257643 is a wasteful number, since it uses less digits than its factorization.

257643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28633 (or 28630 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 257643 is about 507.5854607847. The cubic root of 257643 is about 63.6315910459.

It can be divided in two parts, 257 and 643, that added together give a square (900 = 30²).

The spelling of 257643 in words is "two hundred fifty-seven thousand, six hundred forty-three".