256181 has 2 divisors, whose sum is σ = 256182. Its totient is φ = 256180.

The previous prime is 256169. The next prime is 256187. The reversal of 256181 is 181652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255025 + 1156 = 505^2 + 34^2 .

It is a cyclic number.

It is not a de Polignac number, because 256181 - 2⁶ = 256117 is a prime.

It is a super-2 number, since 2×256181² = 131257409522, which contains 22 as substring.

It is a Chen prime.

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

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 256181.

It is not a weakly prime, because it can be changed into another prime (256187) 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 as a sum of consecutive naturals, namely, 128090 + 128091.

It is an arithmetic number, because the mean of its divisors is an integer number (128091).

2²⁵⁶¹⁸¹ is an apocalyptic number.

It is an amenable number.

256181 is a deficient number, since it is larger than the sum of its proper divisors (1).

256181 is an equidigital number, since it uses as much as digits as its factorization.

256181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 480, while the sum is 23.

The square root of 256181 is about 506.1432603522. The cubic root of 256181 is about 63.5110031153.

Subtracting from 256181 its reverse (181652), we obtain a square (74529 = 273²).

The spelling of 256181 in words is "two hundred fifty-six thousand, one hundred eighty-one".