21123232111 has 4 divisors (see below), whose sum is σ = 21124426392. Its totient is φ = 21122037832.

The previous prime is 21123232099. The next prime is 21123232133. The reversal of 21123232111 is 11123232112.

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-21123232111 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 (21123232171) 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, 570205 + ... + 606118.

It is an arithmetic number, because the mean of its divisors is an integer number (5281106598).

Almost surely, 2^21123232111 is an apocalyptic number.

21123232111 is a deficient number, since it is larger than the sum of its proper divisors (1194281).

21123232111 is a wasteful number, since it uses less digits than its factorization.

21123232111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1194280.

The product of its digits is 144, while the sum is 19.

Adding to 21123232111 its reverse (11123232112), we get a palindrome (32246464223).

Subtracting from 21123232111 its reverse (11123232112), we obtain a palindrome (9999999999).

The spelling of 21123232111 in words is "twenty-one billion, one hundred twenty-three million, two hundred thirty-two thousand, one hundred eleven".