12123100021 has 2 divisors, whose sum is σ = 12123100022. Its totient is φ = 12123100020.

The previous prime is 12123100007. The next prime is 12123100039. The reversal of 12123100021 is 12000132121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6615382225 + 5507717796 = 81335^2 + 74214^2 .

It is a cyclic number.

It is not a de Polignac number, because 12123100021 - 2¹⁹ = 12122575733 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 12123099974 and 12123100010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12123100001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6061550010 + 6061550011.

It is an arithmetic number, because the mean of its divisors is an integer number (6061550011).

Almost surely, 2^12123100021 is an apocalyptic number.

It is an amenable number.

12123100021 is a deficient number, since it is larger than the sum of its proper divisors (1).

12123100021 is an equidigital number, since it uses as much as digits as its factorization.

12123100021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 12123100021 its reverse (12000132121), we get a palindrome (24123232142).

The spelling of 12123100021 in words is "twelve billion, one hundred twenty-three million, one hundred thousand, twenty-one".