21210021111 has 4 divisors (see below), whose sum is σ = 28280028152. Its totient is φ = 14140014072.

The previous prime is 21210021103. The next prime is 21210021137. The reversal of 21210021111 is 11112001212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21210021111 - 2³ = 21210021103 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 (21210021011) 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, 3535003516 + ... + 3535003521.

It is an arithmetic number, because the mean of its divisors is an integer number (7070007038).

Almost surely, 2^21210021111 is an apocalyptic number.

21210021111 is a deficient number, since it is larger than the sum of its proper divisors (7070007041).

21210021111 is an equidigital number, since it uses as much as digits as its factorization.

21210021111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7070007040.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21210021111 its reverse (11112001212), we get a palindrome (32322022323).

The spelling of 21210021111 in words is "twenty-one billion, two hundred ten million, twenty-one thousand, one hundred eleven".