21101211111 has 8 divisors (see below), whose sum is σ = 28895352304. Its totient is φ = 13687272000.

The previous prime is 21101211091. The next prime is 21101211179. The reversal of 21101211111 is 11111210112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21101211111 is a prime.

It is a super-2 number, since 2×21101211111² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101211191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95050390 + ... + 95050611.

It is an arithmetic number, because the mean of its divisors is an integer number (3611919038).

Almost surely, 2^21101211111 is an apocalyptic number.

21101211111 is a deficient number, since it is larger than the sum of its proper divisors (7794141193).

21101211111 is a wasteful number, since it uses less digits than its factorization.

21101211111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190101041.

The product of its (nonzero) digits is 4, while the sum is 12.

Adding to 21101211111 its reverse (11111210112), we get a palindrome (32212421223).

Subtracting from 21101211111 its reverse (11111210112), we obtain a palindrome (9990000999).

The spelling of 21101211111 in words is "twenty-one billion, one hundred one million, two hundred eleven thousand, one hundred eleven".