8221209 has 4 divisors (see below), whose sum is σ = 10961616. Its totient is φ = 5480804.

The previous prime is 8221177. The next prime is 8221211. The reversal of 8221209 is 9021228.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 8221209 - 2⁵ = 8221177 is a prime.

8221209 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (8221219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1370199 + ... + 1370204.

It is an arithmetic number, because the mean of its divisors is an integer number (2740404).

Almost surely, 2^8221209 is an apocalyptic number.

It is an amenable number.

8221209 is a deficient number, since it is larger than the sum of its proper divisors (2740407).

8221209 is a wasteful number, since it uses less digits than its factorization.

8221209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2740406.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 8221209 is about 2867.2650732013. The cubic root of 8221209 is about 201.8266738537.

The spelling of 8221209 in words is "eight million, two hundred twenty-one thousand, two hundred nine".