21210021211111 has 4 divisors (see below), whose sum is σ = 21420021421224. Its totient is φ = 21000021001000.

The previous prime is 21210021211081. The next prime is 21210021211123. The reversal of 21210021211111 is 11111212001212.

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 21210021211111 - 2⁵ = 21210021211079 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 (21210021211711) 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, 105000104905 + ... + 105000105106.

It is an arithmetic number, because the mean of its divisors is an integer number (5355005355306).

Almost surely, 2^{21210021211111} is an apocalyptic number.

21210021211111 is a deficient number, since it is larger than the sum of its proper divisors (210000210113).

21210021211111 is a wasteful number, since it uses less digits than its factorization.

21210021211111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210000210112.

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

Adding to 21210021211111 its reverse (11111212001212), we get a palindrome (32321233212323).

The spelling of 21210021211111 in words is "twenty-one trillion, two hundred ten billion, twenty-one million, two hundred eleven thousand, one hundred eleven".