21211111111211 has 16 divisors (see below), whose sum is σ = 24574458300864. Its totient is φ = 17931083664384.

The previous prime is 21211111111199. The next prime is 21211111111217. The reversal of 21211111111211 is 11211111111212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21211111111211 - 2²⁶ = 21211044002347 is a prime.

It is a super-2 number, since 2×21211111111211² (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 21211111111211.

It is not an unprimeable number, because it can be changed into a prime (21211111111217) 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 15 ways as a sum of consecutive naturals, for example, 10451891 + ... + 12315203.

It is an arithmetic number, because the mean of its divisors is an integer number (1535903643804).

Almost surely, 2^{21211111111211} is an apocalyptic number.

21211111111211 is a deficient number, since it is larger than the sum of its proper divisors (3363347189653).

21211111111211 is a wasteful number, since it uses less digits than its factorization.

21211111111211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1885670.

The product of its digits is 8, while the sum is 17.

Adding to 21211111111211 its reverse (11211111111212), we get a palindrome (32422222222423).

Subtracting from 21211111111211 its reverse (11211111111212), we obtain a palindrome (9999999999999).

The spelling of 21211111111211 in words is "twenty-one trillion, two hundred eleven billion, one hundred eleven million, one hundred eleven thousand, two hundred eleven".