21011111221111 has 8 divisors (see below), whose sum is σ = 22927514515344. Its totient is φ = 19095758305920.

The previous prime is 21011111221049. The next prime is 21011111221183. The reversal of 21011111221111 is 11112211111012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21011111221111 - 2¹⁵ = 21011111188343 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011111221211) 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 in 7 ways as a sum of consecutive naturals, for example, 262552930 + ... + 262632943.

It is an arithmetic number, because the mean of its divisors is an integer number (2865939314418).

Almost surely, 2^{21011111221111} is an apocalyptic number.

21011111221111 is a deficient number, since it is larger than the sum of its proper divisors (1916403294233).

21011111221111 is a wasteful number, since it uses less digits than its factorization.

21011111221111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525189521.

The product of its (nonzero) digits is 8, while the sum is 16.

Adding to 21011111221111 its reverse (11112211111012), we get a palindrome (32123322332123).

The spelling of 21011111221111 in words is "twenty-one trillion, eleven billion, one hundred eleven million, two hundred twenty-one thousand, one hundred eleven".