21212210111111 has 4 divisors (see below), whose sum is σ = 21292864902672. Its totient is φ = 21131555319552.

The previous prime is 21212210111089. The next prime is 21212210111119. The reversal of 21212210111111 is 11111101221212.

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 21212210111111 - 2¹⁰ = 21212210110087 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 21212210111111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212210111119) 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, 40327395386 + ... + 40327395911.

It is an arithmetic number, because the mean of its divisors is an integer number (5323216225668).

Almost surely, 2^{21212210111111} is an apocalyptic number.

21212210111111 is a deficient number, since it is larger than the sum of its proper divisors (80654791561).

21212210111111 is an equidigital number, since it uses as much as digits as its factorization.

21212210111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80654791560.

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

Adding to 21212210111111 its reverse (11111101221212), we get a palindrome (32323311332323).

The spelling of 21212210111111 in words is "twenty-one trillion, two hundred twelve billion, two hundred ten million, one hundred eleven thousand, one hundred eleven".