257405 has 4 divisors (see below), whose sum is σ = 308892. Its totient is φ = 205920.

The previous prime is 257401. The next prime is 257407. The reversal of 257405 is 504752.

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 75076 + 182329 = 274^2 + 427^2 .

It is not a de Polignac number, because 257405 - 2² = 257401 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25736 + ... + 25745.

It is an arithmetic number, because the mean of its divisors is an integer number (77223).

2²⁵⁷⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

257405 is a deficient number, since it is larger than the sum of its proper divisors (51487).

257405 is an equidigital number, since it uses as much as digits as its factorization.

257405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51486.

The product of its (nonzero) digits is 1400, while the sum is 23.

The square root of 257405 is about 507.3509633380. The cubic root of 257405 is about 63.6119915946.

The spelling of 257405 in words is "two hundred fifty-seven thousand, four hundred five".