20121220111 has 24 divisors (see below), whose sum is σ = 22682240640. Its totient is φ = 17806876032.

The previous prime is 20121220103. The next prime is 20121220117. The reversal of 20121220111 is 11102212102.

It is not a de Polignac number, because 20121220111 - 2³ = 20121220103 is a prime.

It is a super-3 number, since 3×20121220111³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20121220091 and 20121220100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121220117) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 366520 + ... + 417826.

It is an arithmetic number, because the mean of its divisors is an integer number (945093360).

Almost surely, 2^20121220111 is an apocalyptic number.

20121220111 is a deficient number, since it is larger than the sum of its proper divisors (2561020529).

20121220111 is a wasteful number, since it uses less digits than its factorization.

20121220111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51423 (or 51406 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 20121220111 its reverse (11102212102), we get a palindrome (31223432213).

The spelling of 20121220111 in words is "twenty billion, one hundred twenty-one million, two hundred twenty thousand, one hundred eleven".