20123111111 has 4 divisors (see below), whose sum is σ = 20124470400. Its totient is φ = 20121751824.

The previous prime is 20123111093. The next prime is 20123111117. The reversal of 20123111111 is 11111132102.

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-20123111111 is a prime.

It is a Duffinian number.

20123111111 is a modest number, since divided by 111111 gives 20123 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20123111117) 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, 657191 + ... + 687128.

It is an arithmetic number, because the mean of its divisors is an integer number (5031117600).

Almost surely, 2^20123111111 is an apocalyptic number.

20123111111 is a deficient number, since it is larger than the sum of its proper divisors (1359289).

20123111111 is a wasteful number, since it uses less digits than its factorization.

20123111111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1359288.

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

Adding to 20123111111 its reverse (11111132102), we get a palindrome (31234243213).

The spelling of 20123111111 in words is "twenty billion, one hundred twenty-three million, one hundred eleven thousand, one hundred eleven".