21001211121211 has 2 divisors, whose sum is σ = 21001211121212. Its totient is φ = 21001211121210.

The previous prime is 21001211121203. The next prime is 21001211121229. The reversal of 21001211121211 is 11212111210012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21001211121211 - 2³ = 21001211121203 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001211121251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500605560605 + 10500605560606.

It is an arithmetic number, because the mean of its divisors is an integer number (10500605560606).

Almost surely, 2^{21001211121211} is an apocalyptic number.

21001211121211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001211121211 is an equidigital number, since it uses as much as digits as its factorization.

21001211121211 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21001211121211 its reverse (11212111210012), we get a palindrome (32213322331223).

The spelling of 21001211121211 in words is "twenty-one trillion, one billion, two hundred eleven million, one hundred twenty-one thousand, two hundred eleven".