257666 has 4 divisors (see below), whose sum is σ = 386502. Its totient is φ = 128832.

The previous prime is 257657. The next prime is 257671. The reversal of 257666 is 666752.

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

It can be written as a sum of positive squares in only one way, i.e., 225625 + 32041 = 475^2 + 179^2 .

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 257666.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64415 + ... + 64418.

2²⁵⁷⁶⁶⁶ is an apocalyptic number.

257666 is a deficient number, since it is larger than the sum of its proper divisors (128836).

257666 is a wasteful number, since it uses less digits than its factorization.

257666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128835.

The product of its digits is 15120, while the sum is 32.

The square root of 257666 is about 507.6081165624. The cubic root of 257666 is about 63.6334844709.

The spelling of 257666 in words is "two hundred fifty-seven thousand, six hundred sixty-six".