12012105821 has 2 divisors, whose sum is σ = 12012105822. Its totient is φ = 12012105820.

The previous prime is 12012105817. The next prime is 12012105827. The reversal of 12012105821 is 12850121021.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8637657721 + 3374448100 = 92939^2 + 58090^2 .

It is a cyclic number.

It is not a de Polignac number, because 12012105821 - 2² = 12012105817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12012105827) 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 as a sum of consecutive naturals, namely, 6006052910 + 6006052911.

It is an arithmetic number, because the mean of its divisors is an integer number (6006052911).

Almost surely, 2^12012105821 is an apocalyptic number.

It is an amenable number.

12012105821 is a deficient number, since it is larger than the sum of its proper divisors (1).

12012105821 is an equidigital number, since it uses as much as digits as its factorization.

12012105821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 320, while the sum is 23.

Adding to 12012105821 its reverse (12850121021), we get a palindrome (24862226842).

The spelling of 12012105821 in words is "twelve billion, twelve million, one hundred five thousand, eight hundred twenty-one".