21103111021 has 2 divisors, whose sum is σ = 21103111022. Its totient is φ = 21103111020.

The previous prime is 21103110997. The next prime is 21103111067. The reversal of 21103111021 is 12011130112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20416408996 + 686702025 = 142886^2 + 26205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103111021 - 2²³ = 21094722413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21103110992 and 21103111010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103141021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551555510 + 10551555511.

It is an arithmetic number, because the mean of its divisors is an integer number (10551555511).

Almost surely, 2^21103111021 is an apocalyptic number.

It is an amenable number.

21103111021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103111021 is an equidigital number, since it uses as much as digits as its factorization.

21103111021 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 13.

Adding to 21103111021 its reverse (12011130112), we get a palindrome (33114241133).

The spelling of 21103111021 in words is "twenty-one billion, one hundred three million, one hundred eleven thousand, twenty-one".