256307881 has 2 divisors, whose sum is σ = 256307882. Its totient is φ = 256307880.

The previous prime is 256307867. The next prime is 256307893. The reversal of 256307881 is 188703652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255840025 + 467856 = 15995^2 + 684^2 .

It is a cyclic number.

It is not a de Polignac number, because 256307881 - 2⁹ = 256307369 is a prime.

It is a super-2 number, since 2×256307881² = 131387459725420322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (256302881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128153940 + 128153941.

It is an arithmetic number, because the mean of its divisors is an integer number (128153941).

Almost surely, 2^256307881 is an apocalyptic number.

It is an amenable number.

256307881 is a deficient number, since it is larger than the sum of its proper divisors (1).

256307881 is an equidigital number, since it uses as much as digits as its factorization.

256307881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80640, while the sum is 40.

The square root of 256307881 is about 16009.6183902053. The cubic root of 256307881 is about 635.2148660104.

The spelling of 256307881 in words is "two hundred fifty-six million, three hundred seven thousand, eight hundred eighty-one".