256881997 has 2 divisors, whose sum is σ = 256881998. Its totient is φ = 256881996.

The previous prime is 256881979. The next prime is 256882001. The reversal of 256881997 is 799188652.

Together with previous prime (256881979) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185749641 + 71132356 = 13629^2 + 8434^2 .

It is a cyclic number.

It is not a de Polignac number, because 256881997 - 2²³ = 248493389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256881907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128440998 + 128440999.

It is an arithmetic number, because the mean of its divisors is an integer number (128440999).

Almost surely, 2^256881997 is an apocalyptic number.

It is an amenable number.

256881997 is a deficient number, since it is larger than the sum of its proper divisors (1).

256881997 is an equidigital number, since it uses as much as digits as its factorization.

256881997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2177280, while the sum is 55.

The square root of 256881997 is about 16027.5387068633. The cubic root of 256881997 is about 635.6887948153.

The spelling of 256881997 in words is "two hundred fifty-six million, eight hundred eighty-one thousand, nine hundred ninety-seven".