209705 has 4 divisors (see below), whose sum is σ = 251652. Its totient is φ = 167760.

The previous prime is 209701. The next prime is 209707. The reversal of 209705 is 507902.

209705 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 507902 = 2 ⋅253951.

It can be written as a sum of positive squares in 2 ways, for example, as 29929 + 179776 = 173^2 + 424^2 .

It is not a de Polignac number, because 209705 - 2² = 209701 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209701) 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, 20966 + ... + 20975.

It is an arithmetic number, because the mean of its divisors is an integer number (62913).

2²⁰⁹⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

209705 is a deficient number, since it is larger than the sum of its proper divisors (41947).

209705 is an equidigital number, since it uses as much as digits as its factorization.

209705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41946.

The product of its (nonzero) digits is 630, while the sum is 23.

The square root of 209705 is about 457.9355849899. The cubic root of 209705 is about 59.4113738343.

The spelling of 209705 in words is "two hundred nine thousand, seven hundred five".