21212102201209 has 2 divisors, whose sum is σ = 21212102201210. Its totient is φ = 21212102201208.

The previous prime is 21212102201201. The next prime is 21212102201281. The reversal of 21212102201209 is 90210220121212.

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., 13899080053609 + 7313022147600 = 3728147^2 + 2704260^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212102201209 - 2³ = 21212102201201 is a prime.

It is a super-3 number, since 3×21212102201209³ (a number of 41 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21212102201201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606051100604 + 10606051100605.

It is an arithmetic number, because the mean of its divisors is an integer number (10606051100605).

Almost surely, 2^{21212102201209} is an apocalyptic number.

It is an amenable number.

21212102201209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212102201209 is an equidigital number, since it uses as much as digits as its factorization.

21212102201209 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 25.

The spelling of 21212102201209 in words is "twenty-one trillion, two hundred twelve billion, one hundred two million, two hundred one thousand, two hundred nine".