256813 has 2 divisors, whose sum is σ = 256814. Its totient is φ = 256812.
The previous prime is 256801. The next prime is 256831. The reversal of 256813 is 318652.
It is a happy number.
Together with next prime (256831) it forms an Ormiston pair, because they use the same digits, order apart.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 145924 + 110889 = 382^2 + 333^2 .
It is a cyclic number.
It is not a de Polignac number, because 256813 - 29 = 256301 is a prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (256873) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128406 + 128407.
It is an arithmetic number, because the mean of its divisors is an integer number (128407).
2256813 is an apocalyptic number.
It is an amenable number.
256813 is a deficient number, since it is larger than the sum of its proper divisors (1).
256813 is an equidigital number, since it uses as much as digits as its factorization.
256813 is an evil number, because the sum of its binary digits is even.
The product of its digits is 1440, while the sum is 25.
The square root of 256813 is about 506.7672049373. The cubic root of 256813 is about 63.5631875623.
The spelling of 256813 in words is "two hundred fifty-six thousand, eight hundred thirteen".
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