21111212210111 has 2 divisors, whose sum is σ = 21111212210112. Its totient is φ = 21111212210110.

The previous prime is 21111212210107. The next prime is 21111212210117. The reversal of 21111212210111 is 11101221211112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21111212210111 - 2² = 21111212210107 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21111212210111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111212210117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555606105055 + 10555606105056.

It is an arithmetic number, because the mean of its divisors is an integer number (10555606105056).

Almost surely, 2^{21111212210111} is an apocalyptic number.

21111212210111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111212210111 is an equidigital number, since it uses as much as digits as its factorization.

21111212210111 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 17.

Adding to 21111212210111 its reverse (11101221211112), we get a palindrome (32212433421223).

The spelling of 21111212210111 in words is "twenty-one trillion, one hundred eleven billion, two hundred twelve million, two hundred ten thousand, one hundred eleven".