21000121211 has 2 divisors, whose sum is σ = 21000121212. Its totient is φ = 21000121210.

The previous prime is 21000121187. The next prime is 21000121217. The reversal of 21000121211 is 11212100012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21000121211 - 2¹⁰ = 21000120187 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21000121192 and 21000121201.

It is not a weakly prime, because it can be changed into another prime (21000121217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500060605 + 10500060606.

It is an arithmetic number, because the mean of its divisors is an integer number (10500060606).

Almost surely, 2^21000121211 is an apocalyptic number.

21000121211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000121211 is an equidigital number, since it uses as much as digits as its factorization.

21000121211 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21000121211 its reverse (11212100012), we get a palindrome (32212221223).

The spelling of 21000121211 in words is "twenty-one billion, one hundred twenty-one thousand, two hundred eleven".