256354991 has 2 divisors, whose sum is σ = 256354992. Its totient is φ = 256354990.

The previous prime is 256354979. The next prime is 256355003. The reversal of 256354991 is 199453652.

It is a balanced prime because it is at equal distance from previous prime (256354979) and next prime (256355003).

It is a cyclic number.

It is not a de Polignac number, because 256354991 - 2⁶ = 256354927 is a prime.

It is a super-2 number, since 2×256354991² = 131435762821220162, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256354291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128177495 + 128177496.

It is an arithmetic number, because the mean of its divisors is an integer number (128177496).

Almost surely, 2^256354991 is an apocalyptic number.

256354991 is a deficient number, since it is larger than the sum of its proper divisors (1).

256354991 is an equidigital number, since it uses as much as digits as its factorization.

256354991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 291600, while the sum is 44.

The square root of 256354991 is about 16011.0896256314. The cubic root of 256354991 is about 635.2537816289.

The spelling of 256354991 in words is "two hundred fifty-six million, three hundred fifty-four thousand, nine hundred ninety-one".