21111031121 has 2 divisors, whose sum is σ = 21111031122. Its totient is φ = 21111031120.

The previous prime is 21111031087. The next prime is 21111031127. The reversal of 21111031121 is 12113011112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18348057025 + 2762974096 = 135455^2 + 52564^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111031121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111031096 and 21111031105.

It is not a weakly prime, because it can be changed into another prime (21111031127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555515560 + 10555515561.

It is an arithmetic number, because the mean of its divisors is an integer number (10555515561).

Almost surely, 2^21111031121 is an apocalyptic number.

It is an amenable number.

21111031121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111031121 is an equidigital number, since it uses as much as digits as its factorization.

21111031121 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21111031121 its reverse (12113011112), we get a palindrome (33224042233).

The spelling of 21111031121 in words is "twenty-one billion, one hundred eleven million, thirty-one thousand, one hundred twenty-one".