21111103121 has 2 divisors, whose sum is σ = 21111103122. Its totient is φ = 21111103120.

The previous prime is 21111103099. The next prime is 21111103133. The reversal of 21111103121 is 12130111112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17459922496 + 3651180625 = 132136^2 + 60425^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111103121 - 2¹⁰ = 21111102097 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111103096 and 21111103105.

It is not a weakly prime, because it can be changed into another prime (21111103721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555551560 + 10555551561.

It is an arithmetic number, because the mean of its divisors is an integer number (10555551561).

Almost surely, 2^21111103121 is an apocalyptic number.

It is an amenable number.

21111103121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111103121 is an equidigital number, since it uses as much as digits as its factorization.

21111103121 is an evil number, because the sum of its binary digits is even.

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

Adding to 21111103121 its reverse (12130111112), we get a palindrome (33241214233).

The spelling of 21111103121 in words is "twenty-one billion, one hundred eleven million, one hundred three thousand, one hundred twenty-one".