21212201209 has 2 divisors, whose sum is σ = 21212201210. Its totient is φ = 21212201208.

The previous prime is 21212201159. The next prime is 21212201279. The reversal of 21212201209 is 90210221212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17363859984 + 3848341225 = 131772^2 + 62035^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212201209 - 2⁹ = 21212200697 is a prime.

It is a super-2 number, since 2×21212201209² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21212201209.

It is not a weakly prime, because it can be changed into another prime (21212201279) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606100604 + 10606100605.

It is an arithmetic number, because the mean of its divisors is an integer number (10606100605).

Almost surely, 2^21212201209 is an apocalyptic number.

It is an amenable number.

21212201209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212201209 is an equidigital number, since it uses as much as digits as its factorization.

21212201209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 22.

The spelling of 21212201209 in words is "twenty-one billion, two hundred twelve million, two hundred one thousand, two hundred nine".