21012001221121 has 2 divisors, whose sum is σ = 21012001221122. Its totient is φ = 21012001221120.

The previous prime is 21012001221097. The next prime is 21012001221187. The reversal of 21012001221121 is 12112210021012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14965787422096 + 6046213799025 = 3868564^2 + 2458905^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012001221121 - 2¹³ = 21012001212929 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21012001221095 and 21012001221104.

It is not a weakly prime, because it can be changed into another prime (21012001221521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506000610560 + 10506000610561.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000610561).

Almost surely, 2^{21012001221121} is an apocalyptic number.

It is an amenable number.

21012001221121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012001221121 is an equidigital number, since it uses as much as digits as its factorization.

21012001221121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21012001221121 its reverse (12112210021012), we get a palindrome (33124211242133).

The spelling of 21012001221121 in words is "twenty-one trillion, twelve billion, one million, two hundred twenty-one thousand, one hundred twenty-one".