12126561581 has 4 divisors (see below), whose sum is σ = 12126850464. Its totient is φ = 12126272700.

The previous prime is 12126561569. The next prime is 12126561583. The reversal of 12126561581 is 18516562121.

12126561581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12126561581 - 2²² = 12122367277 is a prime.

It is a super-2 number, since 2×12126561581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12126561583) 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 in 3 ways as a sum of consecutive naturals, for example, 67985 + ... + 169926.

It is an arithmetic number, because the mean of its divisors is an integer number (3031712616).

Almost surely, 2^12126561581 is an apocalyptic number.

It is an amenable number.

12126561581 is a deficient number, since it is larger than the sum of its proper divisors (288883).

12126561581 is an equidigital number, since it uses as much as digits as its factorization.

12126561581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288882.

The product of its digits is 28800, while the sum is 38.

The spelling of 12126561581 in words is "twelve billion, one hundred twenty-six million, five hundred sixty-one thousand, five hundred eighty-one".