221209 has 2 divisors, whose sum is σ = 221210. Its totient is φ = 221208.

The previous prime is 221203. The next prime is 221219. The reversal of 221209 is 902122.

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., 183184 + 38025 = 428^2 + 195^2 .

It is a cyclic number.

It is not a de Polignac number, because 221209 - 2³ = 221201 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221192 and 221201.

It is not a weakly prime, because it can be changed into another prime (221201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110604 + 110605.

It is an arithmetic number, because the mean of its divisors is an integer number (110605).

2²²¹²⁰⁹ is an apocalyptic number.

It is an amenable number.

221209 is a deficient number, since it is larger than the sum of its proper divisors (1).

221209 is an equidigital number, since it uses as much as digits as its factorization.

221209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 221209 is about 470.3286085281. The cubic root of 221209 is about 60.4784888122.

The spelling of 221209 in words is "two hundred twenty-one thousand, two hundred nine".