20121111111 has 16 divisors (see below), whose sum is σ = 27215014400. Its totient is φ = 13221232128.

The previous prime is 20121111071. The next prime is 20121111119. The reversal of 20121111111 is 11111112102.

It is not a de Polignac number, because 20121111111 - 2¹³ = 20121102919 is a prime.

It is a super-2 number, since 2×20121111111² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

20121111111 is a modest number, since divided by 111111 gives 20121 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121111119) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 63180 + ... + 210318.

It is an arithmetic number, because the mean of its divisors is an integer number (1700938400).

Almost surely, 2^20121111111 is an apocalyptic number.

20121111111 is a deficient number, since it is larger than the sum of its proper divisors (7093903289).

20121111111 is a wasteful number, since it uses less digits than its factorization.

20121111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147798.

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

Adding to 20121111111 its reverse (11111112102), we get a palindrome (31232223213).

Subtracting from 20121111111 its reverse (11111112102), we obtain a palindrome (9009999009).

The spelling of 20121111111 in words is "twenty billion, one hundred twenty-one million, one hundred eleven thousand, one hundred eleven".