21111121211 has 2 divisors, whose sum is σ = 21111121212. Its totient is φ = 21111121210.

The previous prime is 21111121183. The next prime is 21111121219. The reversal of 21111121211 is 11212111112.

It is a m-pointer prime, because the next prime (21111121219) can be obtained adding 21111121211 to its product of digits (8).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21111121211 - 2⁶ = 21111121147 is a prime.

It is not a weakly prime, because it can be changed into another prime (21111121219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555560605 + 10555560606.

It is an arithmetic number, because the mean of its divisors is an integer number (10555560606).

Almost surely, 2^21111121211 is an apocalyptic number.

21111121211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111121211 is an equidigital number, since it uses as much as digits as its factorization.

21111121211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8, while the sum is 14.

Adding to 21111121211 its reverse (11212111112), we get a palindrome (32323232323).

The spelling of 21111121211 in words is "twenty-one billion, one hundred eleven million, one hundred twenty-one thousand, two hundred eleven".