209873 has 4 divisors (see below), whose sum is σ = 217140. Its totient is φ = 202608.

The previous prime is 209861. The next prime is 209887. The reversal of 209873 is 378902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 124609 + 85264 = 353^2 + 292^2 .

It is a cyclic number.

It is not a de Polignac number, because 209873 - 2⁴ = 209857 is a prime.

It is a super-2 number, since 2×209873² = 88093352258, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 7237 = 209873 / (2 + 0 + 9 + 8 + 7 + 3).

It is a Duffinian number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (209813) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3590 + ... + 3647.

It is an arithmetic number, because the mean of its divisors is an integer number (54285).

2²⁰⁹⁸⁷³ is an apocalyptic number.

It is an amenable number.

209873 is a deficient number, since it is larger than the sum of its proper divisors (7267).

209873 is an equidigital number, since it uses as much as digits as its factorization.

209873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7266.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 209873 is about 458.1189801787. The cubic root of 209873 is about 59.4272349195.

Adding to 209873 its sum of digits (29), we get a palindrome (209902).

The spelling of 209873 in words is "two hundred nine thousand, eight hundred seventy-three".