21121111220111 has 4 divisors (see below), whose sum is σ = 24138412822992. Its totient is φ = 18103809617232.

The previous prime is 21121111220093. The next prime is 21121111220147. The reversal of 21121111220111 is 11102211112112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121111220111 is a prime.

It is a super-2 number, since 2×21121111220111² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21121111220111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121111240111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1508650801430 + ... + 1508650801443.

It is an arithmetic number, because the mean of its divisors is an integer number (6034603205748).

Almost surely, 2^{21121111220111} is an apocalyptic number.

21121111220111 is a deficient number, since it is larger than the sum of its proper divisors (3017301602881).

21121111220111 is an equidigital number, since it uses as much as digits as its factorization.

21121111220111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3017301602880.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 21121111220111 its reverse (11102211112112), we get a palindrome (32223322332223).

The spelling of 21121111220111 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred eleven million, two hundred twenty thousand, one hundred eleven".