256221 has 24 divisors (see below), whose sum is σ = 436800. Its totient is φ = 144648.

The previous prime is 256219. The next prime is 256279. The reversal of 256221 is 122652.

It is not a de Polignac number, because 256221 - 2¹ = 256219 is a prime.

It is a Curzon number.

256221 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 256194 and 256203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256211) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3046 + ... + 3128.

It is an arithmetic number, because the mean of its divisors is an integer number (18200).

2²⁵⁶²²¹ is an apocalyptic number.

256221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

256221 is a deficient number, since it is larger than the sum of its proper divisors (180579).

256221 is an equidigital number, since it uses as much as digits as its factorization.

256221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110 (or 93 counting only the distinct ones).

The product of its digits is 240, while the sum is 18.

The square root of 256221 is about 506.1827733141. The cubic root of 256221 is about 63.5143084709.

Adding to 256221 its reverse (122652), we get a palindrome (378873).

The spelling of 256221 in words is "two hundred fifty-six thousand, two hundred twenty-one".