256820 has 12 divisors (see below), whose sum is σ = 539364. Its totient is φ = 102720.

The previous prime is 256813. The next prime is 256831. The reversal of 256820 is 28652.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 106276 + 150544 = 326^2 + 388^2 .

It is a hoax number, since the sum of its digits (23) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

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, 6401 + ... + 6440.

It is an arithmetic number, because the mean of its divisors is an integer number (44947).

2²⁵⁶⁸²⁰ is an apocalyptic number.

256820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256820 is an abundant number, since it is smaller than the sum of its proper divisors (282544).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256820 is a wasteful number, since it uses less digits than its factorization.

256820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12850 (or 12848 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 256820 is about 506.7741114145. The cubic root of 256820 is about 63.5637650750.

It can be divided in two parts, 2568 and 20, that multiplied together give a triangular number (51360 = T₃₂₀).

The spelling of 256820 in words is "two hundred fifty-six thousand, eight hundred twenty".