21210221121209 has 2 divisors, whose sum is σ = 21210221121210. Its totient is φ = 21210221121208.

The previous prime is 21210221121191. The next prime is 21210221121217. The reversal of 21210221121209 is 90212112201212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16657801471609 + 4552419649600 = 4081397^2 + 2133640^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210221121209 - 2⁸ = 21210221120953 is a prime.

It is not a weakly prime, because it can be changed into another prime (21210221121239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605110560604 + 10605110560605.

It is an arithmetic number, because the mean of its divisors is an integer number (10605110560605).

Almost surely, 2^{21210221121209} is an apocalyptic number.

It is an amenable number.

21210221121209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210221121209 is an equidigital number, since it uses as much as digits as its factorization.

21210221121209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 26.

The spelling of 21210221121209 in words is "twenty-one trillion, two hundred ten billion, two hundred twenty-one million, one hundred twenty-one thousand, two hundred nine".