256705 has 4 divisors (see below), whose sum is σ = 308052. Its totient is φ = 205360.

The previous prime is 256699. The next prime is 256721. The reversal of 256705 is 507652.

It is a happy number.

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 153664 + 103041 = 392^2 + 321^2 .

It is not a de Polignac number, because 256705 - 2⁷ = 256577 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

256705 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 256705.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25666 + ... + 25675.

It is an arithmetic number, because the mean of its divisors is an integer number (77013).

2²⁵⁶⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

256705 is a deficient number, since it is larger than the sum of its proper divisors (51347).

256705 is an equidigital number, since it uses as much as digits as its factorization.

256705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51346.

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 256705 is about 506.6606359290. The cubic root of 256705 is about 63.5542760368.

It can be divided in two parts, 256 and 705, that added together give a square (961 = 31²).

The spelling of 256705 in words is "two hundred fifty-six thousand, seven hundred five".