257638 has 4 divisors (see below), whose sum is σ = 386460. Its totient is φ = 128818.

The previous prime is 257627. The next prime is 257639. The reversal of 257638 is 836752.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257639) by changing a digit.

257638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64408 + ... + 64411.

It is an arithmetic number, because the mean of its divisors is an integer number (96615).

2²⁵⁷⁶³⁸ is an apocalyptic number.

257638 is a deficient number, since it is larger than the sum of its proper divisors (128822).

257638 is a wasteful number, since it uses less digits than its factorization.

257638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128821.

The product of its digits is 10080, while the sum is 31.

The square root of 257638 is about 507.5805354818. The cubic root of 257638 is about 63.6311794169.

The spelling of 257638 in words is "two hundred fifty-seven thousand, six hundred thirty-eight".