21001221122111 has 2 divisors, whose sum is σ = 21001221122112. Its totient is φ = 21001221122110.

The previous prime is 21001221122053. The next prime is 21001221122113. The reversal of 21001221122111 is 11122112210012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001221122111 is a prime.

Together with 21001221122113, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001221122111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001221122113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500610561055 + 10500610561056.

It is an arithmetic number, because the mean of its divisors is an integer number (10500610561056).

Almost surely, 2^{21001221122111} is an apocalyptic number.

21001221122111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001221122111 is an equidigital number, since it uses as much as digits as its factorization.

21001221122111 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 17.

Adding to 21001221122111 its reverse (11122112210012), we get a palindrome (32123333332123).

The spelling of 21001221122111 in words is "twenty-one trillion, one billion, two hundred twenty-one million, one hundred twenty-two thousand, one hundred eleven".