21210221111111 has 4 divisors (see below), whose sum is σ = 21210230902224. Its totient is φ = 21210211320000.

The previous prime is 21210221111099. The next prime is 21210221111113. The reversal of 21210221111111 is 11111112201212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21210221111111 - 2⁶ = 21210221111047 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 21210221111111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210221111113) 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, 42515 + ... + 6513236.

It is an arithmetic number, because the mean of its divisors is an integer number (5302557725556).

Almost surely, 2^{21210221111111} is an apocalyptic number.

21210221111111 is a deficient number, since it is larger than the sum of its proper divisors (9791113).

21210221111111 is an equidigital number, since it uses as much as digits as its factorization.

21210221111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9791112.

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

Adding to 21210221111111 its reverse (11111112201212), we get a palindrome (32321333312323).

The spelling of 21210221111111 in words is "twenty-one trillion, two hundred ten billion, two hundred twenty-one million, one hundred eleven thousand, one hundred eleven".