20121011111 has 4 divisors (see below), whose sum is σ = 20151824952. Its totient is φ = 20090197272.

The previous prime is 20121011083. The next prime is 20121011137. The reversal of 20121011111 is 11111012102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11111012102 = 2 ⋅5555506051.

It is a cyclic number.

It is not a de Polignac number, because 20121011111 - 2¹⁴ = 20120994727 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20121011092 and 20121011101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121011411) 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, 15405941 + ... + 15407246.

It is an arithmetic number, because the mean of its divisors is an integer number (5037956238).

Almost surely, 2^20121011111 is an apocalyptic number.

20121011111 is a deficient number, since it is larger than the sum of its proper divisors (30813841).

20121011111 is an equidigital number, since it uses as much as digits as its factorization.

20121011111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30813840.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 20121011111 its reverse (11111012102), we get a palindrome (31232023213).

Subtracting from 20121011111 its reverse (11111012102), we obtain a palindrome (9009999009).

The spelling of 20121011111 in words is "twenty billion, one hundred twenty-one million, eleven thousand, one hundred eleven".