20111111021 has 2 divisors, whose sum is σ = 20111111022. Its totient is φ = 20111111020.

The previous prime is 20111111003. The next prime is 20111111039. The reversal of 20111111021 is 12011111102.

It is a balanced prime because it is at equal distance from previous prime (20111111003) and next prime (20111111039).

It can be written as a sum of positive squares in only one way, i.e., 19990000996 + 121110025 = 141386^2 + 11005^2 .

It is a cyclic number.

It is not a de Polignac number, because 20111111021 - 2³⁴ = 2931241837 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20111110993 and 20111111011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20111111071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055555510 + 10055555511.

It is an arithmetic number, because the mean of its divisors is an integer number (10055555511).

Almost surely, 2^20111111021 is an apocalyptic number.

It is an amenable number.

20111111021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20111111021 is an equidigital number, since it uses as much as digits as its factorization.

20111111021 is an odious number, because the sum of its binary digits is odd.

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

Adding to 20111111021 its reverse (12011111102), we get a palindrome (32122222123).

The spelling of 20111111021 in words is "twenty billion, one hundred eleven million, one hundred eleven thousand, twenty-one".