256540243213 has 2 divisors, whose sum is σ = 256540243214. Its totient is φ = 256540243212.

The previous prime is 256540243199. The next prime is 256540243261. The reversal of 256540243213 is 312342045652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216599021604 + 39941221609 = 465402^2 + 199853^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256540243213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256540243913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128270121606 + 128270121607.

It is an arithmetic number, because the mean of its divisors is an integer number (128270121607).

Almost surely, 2^256540243213 is an apocalyptic number.

It is an amenable number.

256540243213 is a deficient number, since it is larger than the sum of its proper divisors (1).

256540243213 is an equidigital number, since it uses as much as digits as its factorization.

256540243213 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 172800, while the sum is 37.

Adding to 256540243213 its reverse (312342045652), we get a palindrome (568882288865).

The spelling of 256540243213 in words is "two hundred fifty-six billion, five hundred forty million, two hundred forty-three thousand, two hundred thirteen".