12561263321 has 4 divisors (see below), whose sum is σ = 12588750132. Its totient is φ = 12533776512.

The previous prime is 12561263249. The next prime is 12561263347. The reversal of 12561263321 is 12336216521.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12336216521 = 2029 ⋅6079949.

It can be written as a sum of positive squares in 2 ways, for example, as 9557017600 + 3004245721 = 97760^2 + 54811^2 .

It is a cyclic number.

It is not a de Polignac number, because 12561263321 - 2²⁶ = 12494154457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12561263021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13742720 + ... + 13743633.

It is an arithmetic number, because the mean of its divisors is an integer number (3147187533).

Almost surely, 2^12561263321 is an apocalyptic number.

It is an amenable number.

12561263321 is a deficient number, since it is larger than the sum of its proper divisors (27486811).

12561263321 is an equidigital number, since it uses as much as digits as its factorization.

12561263321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27486810.

The product of its digits is 12960, while the sum is 32.

Adding to 12561263321 its reverse (12336216521), we get a palindrome (24897479842).

The spelling of 12561263321 in words is "twelve billion, five hundred sixty-one million, two hundred sixty-three thousand, three hundred twenty-one".