12561224161 has 4 divisors (see below), whose sum is σ = 12867595524. Its totient is φ = 12254852800.

The previous prime is 12561224147. The next prime is 12561224167. The reversal of 12561224161 is 16142216521.

It is a happy number.

12561224161 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 an emirpimes, since its reverse is a distinct semiprime: 16142216521 = 17107 ⋅943603.

It can be written as a sum of positive squares in 2 ways, for example, as 2557223761 + 10004000400 = 50569^2 + 100020^2 .

It is a cyclic number.

It is not a de Polignac number, because 12561224161 - 2¹⁵ = 12561191393 is a prime.

It is a Smith number, since the sum of its digits (31) 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 not an unprimeable number, because it can be changed into a prime (12561224167) 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, 153185620 + ... + 153185701.

It is an arithmetic number, because the mean of its divisors is an integer number (3216898881).

Almost surely, 2^12561224161 is an apocalyptic number.

It is an amenable number.

12561224161 is a deficient number, since it is larger than the sum of its proper divisors (306371363).

12561224161 is an equidigital number, since it uses as much as digits as its factorization.

12561224161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306371362.

The product of its digits is 5760, while the sum is 31.

The spelling of 12561224161 in words is "twelve billion, five hundred sixty-one million, two hundred twenty-four thousand, one hundred sixty-one".