256691543 has 2 divisors, whose sum is σ = 256691544. Its totient is φ = 256691542.

The previous prime is 256691507. The next prime is 256691587. The reversal of 256691543 is 345196652.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256691543 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256691543.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256691593) 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, 128345771 + 128345772.

It is an arithmetic number, because the mean of its divisors is an integer number (128345772).

Almost surely, 2^256691543 is an apocalyptic number.

256691543 is a deficient number, since it is larger than the sum of its proper divisors (1).

256691543 is an equidigital number, since it uses as much as digits as its factorization.

256691543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 194400, while the sum is 41.

The square root of 256691543 is about 16021.5961439552. The cubic root of 256691543 is about 635.5316546913.

The spelling of 256691543 in words is "two hundred fifty-six million, six hundred ninety-one thousand, five hundred forty-three".