21210312111 has 4 divisors (see below), whose sum is σ = 28280416152. Its totient is φ = 14140208072.

The previous prime is 21210312083. The next prime is 21210312181. The reversal of 21210312111 is 11121301212.

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 21210312111 - 2⁹ = 21210311599 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210312181) 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, 3535052016 + ... + 3535052021.

It is an arithmetic number, because the mean of its divisors is an integer number (7070104038).

Almost surely, 2^21210312111 is an apocalyptic number.

21210312111 is a deficient number, since it is larger than the sum of its proper divisors (7070104041).

21210312111 is an equidigital number, since it uses as much as digits as its factorization.

21210312111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7070104040.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21210312111 its reverse (11121301212), we get a palindrome (32331613323).

The spelling of 21210312111 in words is "twenty-one billion, two hundred ten million, three hundred twelve thousand, one hundred eleven".