21111211210211 has 4 divisors (see below), whose sum is σ = 21111591942792. Its totient is φ = 21110830477632.

The previous prime is 21111211210207. The next prime is 21111211210217. The reversal of 21111211210211 is 11201211211112.

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

It is a cyclic number.

It is not a de Polignac number, because 21111211210211 - 2² = 21111211210207 is a prime.

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 21111211210211.

It is not an unprimeable number, because it can be changed into a prime (21111211210217) 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, 190283105 + ... + 190394018.

It is an arithmetic number, because the mean of its divisors is an integer number (5277897985698).

Almost surely, 2^{21111211210211} is an apocalyptic number.

21111211210211 is a deficient number, since it is larger than the sum of its proper divisors (380732581).

21111211210211 is an equidigital number, since it uses as much as digits as its factorization.

21111211210211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 380732580.

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

Adding to 21111211210211 its reverse (11201211211112), we get a palindrome (32312422421323).

Subtracting from 21111211210211 its reverse (11201211211112), we obtain a palindrome (9909999999099).

The spelling of 21111211210211 in words is "twenty-one trillion, one hundred eleven billion, two hundred eleven million, two hundred ten thousand, two hundred eleven".