21213131111 has 4 divisors (see below), whose sum is σ = 21221976000. Its totient is φ = 21204286224.

The previous prime is 21213131083. The next prime is 21213131123. The reversal of 21213131111 is 11113131212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213131111 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 21213131111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213131141) 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, 4418846 + ... + 4423643.

It is an arithmetic number, because the mean of its divisors is an integer number (5305494000).

Almost surely, 2^21213131111 is an apocalyptic number.

21213131111 is a deficient number, since it is larger than the sum of its proper divisors (8844889).

21213131111 is an equidigital number, since it uses as much as digits as its factorization.

21213131111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8844888.

The product of its digits is 36, while the sum is 17.

Adding to 21213131111 its reverse (11113131212), we get a palindrome (32326262323).

The spelling of 21213131111 in words is "twenty-one billion, two hundred thirteen million, one hundred thirty-one thousand, one hundred eleven".