209686221 has 6 divisors (see below), whose sum is σ = 302880110. Its totient is φ = 139790808.

The previous prime is 209686199. The next prime is 209686229. The reversal of 209686221 is 122686902.

It is a happy number.

209686221 is a `hidden beast` number, since 20 + 9 + 6 + 8 + 622 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 208658025 + 1028196 = 14445^2 + 1014^2 .

It is not a de Polignac number, because 209686221 - 2⁷ = 209686093 is a prime.

It is a super-2 number, since 2×209686221² = 87936622554521682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209686229) 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, 11649226 + ... + 11649243.

Almost surely, 2^209686221 is an apocalyptic number.

It is an amenable number.

209686221 is a deficient number, since it is larger than the sum of its proper divisors (93193889).

209686221 is a wasteful number, since it uses less digits than its factorization.

209686221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23298475 (or 23298472 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 209686221 is about 14480.5462949434. The cubic root of 209686221 is about 594.0960035965.

The spelling of 209686221 in words is "two hundred nine million, six hundred eighty-six thousand, two hundred twenty-one".