21030212209 has 2 divisors, whose sum is σ = 21030212210. Its totient is φ = 21030212208.

The previous prime is 21030212207. The next prime is 21030212267. The reversal of 21030212209 is 90221203012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15613252209 + 5416960000 = 124953^2 + 73600^2 .

It is a cyclic number.

It is not a de Polignac number, because 21030212209 - 2¹ = 21030212207 is a prime.

Together with 21030212207, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21030212209.

It is not a weakly prime, because it can be changed into another prime (21030212207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515106104 + 10515106105.

It is an arithmetic number, because the mean of its divisors is an integer number (10515106105).

Almost surely, 2^21030212209 is an apocalyptic number.

It is an amenable number.

21030212209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21030212209 is an equidigital number, since it uses as much as digits as its factorization.

21030212209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The spelling of 21030212209 in words is "twenty-one billion, thirty million, two hundred twelve thousand, two hundred nine".