212221409 has 2 divisors, whose sum is σ = 212221410. Its totient is φ = 212221408.

The previous prime is 212221397. The next prime is 212221411. The reversal of 212221409 is 904122212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164224225 + 47997184 = 12815^2 + 6928^2 .

It is a cyclic number.

It is not a de Polignac number, because 212221409 - 2⁸ = 212221153 is a prime.

Together with 212221411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (212221459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106110704 + 106110705.

It is an arithmetic number, because the mean of its divisors is an integer number (106110705).

Almost surely, 2^212221409 is an apocalyptic number.

It is an amenable number.

212221409 is a deficient number, since it is larger than the sum of its proper divisors (1).

212221409 is an equidigital number, since it uses as much as digits as its factorization.

212221409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 212221409 is about 14567.8210107071. The cubic root of 212221409 is about 596.4807025649.

The spelling of 212221409 in words is "two hundred twelve million, two hundred twenty-one thousand, four hundred nine".