209997 has 6 divisors (see below), whose sum is σ = 303342. Its totient is φ = 139992.

The previous prime is 209987. The next prime is 210011. The reversal of 209997 is 799902.

209997 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 125316 + 84681 = 354^2 + 291^2 .

It is not a de Polignac number, because 209997 - 2¹⁶ = 144461 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209917) 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, 11658 + ... + 11675.

It is an arithmetic number, because the mean of its divisors is an integer number (50557).

2²⁰⁹⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

209997 is a deficient number, since it is larger than the sum of its proper divisors (93345).

209997 is a wasteful number, since it uses less digits than its factorization.

209997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23339 (or 23336 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 36.

The square root of 209997 is about 458.2542962155. The cubic root of 209997 is about 59.4389364824.

The spelling of 209997 in words is "two hundred nine thousand, nine hundred ninety-seven".