1256536513 has 2 divisors, whose sum is σ = 1256536514. Its totient is φ = 1256536512.

The previous prime is 1256536451. The next prime is 1256536531. The reversal of 1256536513 is 3156356521.

Together with next prime (1256536531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 759112704 + 497423809 = 27552^2 + 22303^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1256536513 is a prime.

It is not a weakly prime, because it can be changed into another prime (1256533513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628268256 + 628268257.

It is an arithmetic number, because the mean of its divisors is an integer number (628268257).

Almost surely, 2^1256536513 is an apocalyptic number.

It is an amenable number.

1256536513 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256536513 is an equidigital number, since it uses as much as digits as its factorization.

1256536513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81000, while the sum is 37.

The square root of 1256536513 is about 35447.6587802354. The cubic root of 1256536513 is about 1079.0917469698.

The spelling of 1256536513 in words is "one billion, two hundred fifty-six million, five hundred thirty-six thousand, five hundred thirteen".