256647 has 4 divisors (see below), whose sum is σ = 342200. Its totient is φ = 171096.

The previous prime is 256643. The next prime is 256651. The reversal of 256647 is 746652.

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

It is an interprime number because it is at equal distance from previous prime (256643) and next prime (256651).

It is not a de Polignac number, because 256647 - 2² = 256643 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42772 + ... + 42777.

It is an arithmetic number, because the mean of its divisors is an integer number (85550).

2²⁵⁶⁶⁴⁷ is an apocalyptic number.

256647 is a deficient number, since it is larger than the sum of its proper divisors (85553).

256647 is an equidigital number, since it uses as much as digits as its factorization.

256647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85552.

The product of its digits is 10080, while the sum is 30.

The square root of 256647 is about 506.6033951722. The cubic root of 256647 is about 63.5494891859.

It can be divided in two parts, 256 and 647, that added together give a triangular number (903 = T₄₂).

The spelling of 256647 in words is "two hundred fifty-six thousand, six hundred forty-seven".