21101111123 has 4 divisors (see below), whose sum is σ = 21101899248. Its totient is φ = 21100323000.

The previous prime is 21101111113. The next prime is 21101111149. The reversal of 21101111123 is 32111110112.

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 21101111123 - 2⁴ = 21101111107 is a prime.

It is a super-2 number, since 2×21101111123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101111098 and 21101111107.

It is not an unprimeable number, because it can be changed into a prime (21101111113) 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, 352436 + ... + 407937.

It is an arithmetic number, because the mean of its divisors is an integer number (5275474812).

Almost surely, 2^21101111123 is an apocalyptic number.

21101111123 is a deficient number, since it is larger than the sum of its proper divisors (788125).

21101111123 is an equidigital number, since it uses as much as digits as its factorization.

21101111123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 788124.

The product of its (nonzero) digits is 12, while the sum is 14.

Adding to 21101111123 its reverse (32111110112), we get a palindrome (53212221235).

The spelling of 21101111123 in words is "twenty-one billion, one hundred one million, one hundred eleven thousand, one hundred twenty-three".