21211001221121 has 2 divisors, whose sum is σ = 21211001221122. Its totient is φ = 21211001221120.

The previous prime is 21211001220977. The next prime is 21211001221139. The reversal of 21211001221121 is 12112210011212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14096570611600 + 7114430609521 = 3754540^2 + 2667289^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211001221121 - 2²⁶ = 21210934112257 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21211001221121.

It is not a weakly prime, because it can be changed into another prime (21211001221141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605500610560 + 10605500610561.

It is an arithmetic number, because the mean of its divisors is an integer number (10605500610561).

Almost surely, 2^{21211001221121} is an apocalyptic number.

It is an amenable number.

21211001221121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211001221121 is an equidigital number, since it uses as much as digits as its factorization.

21211001221121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21211001221121 its reverse (12112210011212), we get a palindrome (33323211232333).

The spelling of 21211001221121 in words is "twenty-one trillion, two hundred eleven billion, one million, two hundred twenty-one thousand, one hundred twenty-one".