13261326565 has 4 divisors (see below), whose sum is σ = 15913591884. Its totient is φ = 10609061248.

The previous prime is 13261326523. The next prime is 13261326571. The reversal of 13261326565 is 56562316231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56562316231 = 887 ⋅63768113.

It can be written as a sum of positive squares in 2 ways, for example, as 10256423076 + 3004903489 = 101274^2 + 54817^2 .

It is a cyclic number.

It is not a de Polignac number, because 13261326565 - 2⁷ = 13261326437 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1326132652 + ... + 1326132661.

It is an arithmetic number, because the mean of its divisors is an integer number (3978397971).

Almost surely, 2^13261326565 is an apocalyptic number.

It is an amenable number.

13261326565 is a deficient number, since it is larger than the sum of its proper divisors (2652265319).

13261326565 is an equidigital number, since it uses as much as digits as its factorization.

13261326565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2652265318.

The product of its digits is 194400, while the sum is 40.

The spelling of 13261326565 in words is "thirteen billion, two hundred sixty-one million, three hundred twenty-six thousand, five hundred sixty-five".