209965221 has 6 divisors (see below), whose sum is σ = 303283110. Its totient is φ = 139976808.

The previous prime is 209965213. The next prime is 209965237. The reversal of 209965221 is 122569902.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 126900225 + 83064996 = 11265^2 + 9114^2 .

It is not a de Polignac number, because 209965221 - 2³ = 209965213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209965271) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11664726 + ... + 11664743.

It is an arithmetic number, because the mean of its divisors is an integer number (50547185).

Almost surely, 2^209965221 is an apocalyptic number.

It is an amenable number.

209965221 is a deficient number, since it is larger than the sum of its proper divisors (93317889).

209965221 is a wasteful number, since it uses less digits than its factorization.

209965221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23329475 (or 23329472 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 209965221 is about 14490.1767069971. The cubic root of 209965221 is about 594.3593801851.

The spelling of 209965221 in words is "two hundred nine million, nine hundred sixty-five thousand, two hundred twenty-one".