256720 has 20 divisors (see below), whose sum is σ = 597060. Its totient is φ = 102656.

The previous prime is 256699. The next prime is 256721. The reversal of 256720 is 27652.

256720 is nontrivially palindromic in base 9.

It can be written as a sum of positive squares in 2 ways, for example, as 118336 + 138384 = 344^2 + 372^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a nialpdrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 256691 and 256700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256721) 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, 1525 + ... + 1684.

It is an arithmetic number, because the mean of its divisors is an integer number (29853).

2²⁵⁶⁷²⁰ is an apocalyptic number.

256720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256720 is an abundant number, since it is smaller than the sum of its proper divisors (340340).

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

256720 is a wasteful number, since it uses less digits than its factorization.

256720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3222 (or 3216 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 256720 is about 506.6754385206. The cubic root of 256720 is about 63.5555138981. Note that the first 4 decimals are identical.

The spelling of 256720 in words is "two hundred fifty-six thousand, seven hundred twenty".