21210211111 has 4 divisors (see below), whose sum is σ = 21227698072. Its totient is φ = 21192724152.

The previous prime is 21210211103. The next prime is 21210211123. The reversal of 21210211111 is 11111201212.

It is a happy number.

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 21210211111 - 2³ = 21210211103 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210211091 and 21210211100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210214111) 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, 8741661 + ... + 8744086.

It is an arithmetic number, because the mean of its divisors is an integer number (5306924518).

Almost surely, 2^21210211111 is an apocalyptic number.

21210211111 is a deficient number, since it is larger than the sum of its proper divisors (17486961).

21210211111 is a wasteful number, since it uses less digits than its factorization.

21210211111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17486960.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21210211111 its reverse (11111201212), we get a palindrome (32321412323).

The spelling of 21210211111 in words is "twenty-one billion, two hundred ten million, two hundred eleven thousand, one hundred eleven".