21122123111 has 4 divisors (see below), whose sum is σ = 21283360824. Its totient is φ = 20960885400.

The previous prime is 21122123101. The next prime is 21122123119. The reversal of 21122123111 is 11132122112.

It is a happy number.

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-21122123111 is a prime.

It is a super-2 number, since 2×21122123111² (a number of 21 digits) contains 22 as substring.

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 21122123111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122123119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80618660 + ... + 80618921.

It is an arithmetic number, because the mean of its divisors is an integer number (5320840206).

Almost surely, 2^21122123111 is an apocalyptic number.

21122123111 is a deficient number, since it is larger than the sum of its proper divisors (161237713).

21122123111 is a wasteful number, since it uses less digits than its factorization.

21122123111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161237712.

The product of its digits is 48, while the sum is 17.

Adding to 21122123111 its reverse (11132122112), we get a palindrome (32254245223).

Subtracting from 21122123111 its reverse (11132122112), we obtain a palindrome (9990000999).

The spelling of 21122123111 in words is "twenty-one billion, one hundred twenty-two million, one hundred twenty-three thousand, one hundred eleven".