256533491 has 2 divisors, whose sum is σ = 256533492. Its totient is φ = 256533490.

The previous prime is 256533481. The next prime is 256533493. The reversal of 256533491 is 194335652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256533491 - 2⁶ = 256533427 is a prime.

Together with 256533493, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (256533493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128266745 + 128266746.

It is an arithmetic number, because the mean of its divisors is an integer number (128266746).

Almost surely, 2^256533491 is an apocalyptic number.

256533491 is a deficient number, since it is larger than the sum of its proper divisors (1).

256533491 is an equidigital number, since it uses as much as digits as its factorization.

256533491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 97200, while the sum is 38.

The square root of 256533491 is about 16016.6629170998. The cubic root of 256533491 is about 635.4011898398.

The spelling of 256533491 in words is "two hundred fifty-six million, five hundred thirty-three thousand, four hundred ninety-one".