12523655561 has 4 divisors (see below), whose sum is σ = 12532545300. Its totient is φ = 12514765824.

The previous prime is 12523655531. The next prime is 12523655563. The reversal of 12523655561 is 16555632521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16555632521 = 137 ⋅120844033.

It can be written as a sum of positive squares in 2 ways, for example, as 2592337225 + 9931318336 = 50915^2 + 99656^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12523655561 is a prime.

It is a super-2 number, since 2×12523655561² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12523655563) by changing a digit.

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, 4442756 + ... + 4445573.

It is an arithmetic number, because the mean of its divisors is an integer number (3133136325).

Almost surely, 2^12523655561 is an apocalyptic number.

It is an amenable number.

12523655561 is a deficient number, since it is larger than the sum of its proper divisors (8889739).

12523655561 is an equidigital number, since it uses as much as digits as its factorization.

12523655561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8889738.

The product of its digits is 270000, while the sum is 41.

The spelling of 12523655561 in words is "twelve billion, five hundred twenty-three million, six hundred fifty-five thousand, five hundred sixty-one".