256871491 has 2 divisors, whose sum is σ = 256871492. Its totient is φ = 256871490.

The previous prime is 256871477. The next prime is 256871569. The reversal of 256871491 is 194178652.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256871491 is a prime.

It is not a weakly prime, because it can be changed into another prime (256871401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128435745 + 128435746.

It is an arithmetic number, because the mean of its divisors is an integer number (128435746).

Almost surely, 2^256871491 is an apocalyptic number.

256871491 is a deficient number, since it is larger than the sum of its proper divisors (1).

256871491 is an equidigital number, since it uses as much as digits as its factorization.

256871491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 43.

The square root of 256871491 is about 16027.2109551225. The cubic root of 256871491 is about 635.6801285307.

The spelling of 256871491 in words is "two hundred fifty-six million, eight hundred seventy-one thousand, four hundred ninety-one".