21010221121 has 2 divisors, whose sum is σ = 21010221122. Its totient is φ = 21010221120.

The previous prime is 21010221073. The next prime is 21010221131. The reversal of 21010221121 is 12112201012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15765564721 + 5244656400 = 125561^2 + 72420^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010221121 - 2⁷ = 21010220993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21010221131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505110560 + 10505110561.

It is an arithmetic number, because the mean of its divisors is an integer number (10505110561).

Almost surely, 2^21010221121 is an apocalyptic number.

It is an amenable number.

21010221121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010221121 is an equidigital number, since it uses as much as digits as its factorization.

21010221121 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21010221121 its reverse (12112201012), we get a palindrome (33122422133).

The spelling of 21010221121 in words is "twenty-one billion, ten million, two hundred twenty-one thousand, one hundred twenty-one".