21121210212209 has 2 divisors, whose sum is σ = 21121210212210. Its totient is φ = 21121210212208.

The previous prime is 21121210212197. The next prime is 21121210212233. The reversal of 21121210212209 is 90221201212112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21054011056225 + 67199155984 = 4588465^2 + 259228^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121210212209 - 2⁸ = 21121210211953 is a prime.

It is a super-2 number, since 2×21121210212209² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121210212409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560605106104 + 10560605106105.

It is an arithmetic number, because the mean of its divisors is an integer number (10560605106105).

Almost surely, 2^{21121210212209} is an apocalyptic number.

It is an amenable number.

21121210212209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121210212209 is an equidigital number, since it uses as much as digits as its factorization.

21121210212209 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 21121210212209 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred ten million, two hundred twelve thousand, two hundred nine".