209839221 has 8 divisors (see below), whose sum is σ = 310872960. Its totient is φ = 139892796.

The previous prime is 209839219. The next prime is 209839237. The reversal of 209839221 is 122938902.

It is not a de Polignac number, because 209839221 - 2¹ = 209839219 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209839241) 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 7 ways as a sum of consecutive naturals, for example, 3885885 + ... + 3885938.

It is an arithmetic number, because the mean of its divisors is an integer number (38859120).

Almost surely, 2^209839221 is an apocalyptic number.

It is an amenable number.

209839221 is a deficient number, since it is larger than the sum of its proper divisors (101033739).

209839221 is an equidigital number, since it uses as much as digits as its factorization.

209839221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7771832 (or 7771826 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 209839221 is about 14485.8282814619. The cubic root of 209839221 is about 594.2404648287.

The spelling of 209839221 in words is "two hundred nine million, eight hundred thirty-nine thousand, two hundred twenty-one".