105209 has 4 divisors (see below), whose sum is σ = 113316. Its totient is φ = 97104.

The previous prime is 105199. The next prime is 105211. The reversal of 105209 is 902501.

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 29584 + 75625 = 172^2 + 275^2 .

It is a cyclic number.

It is not a de Polignac number, because 105209 - 2⁸ = 104953 is a prime.

It is a super-2 number, since 2×105209² = 22137867362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (105229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4034 + ... + 4059.

It is an arithmetic number, because the mean of its divisors is an integer number (28329).

2¹⁰⁵²⁰⁹ is an apocalyptic number.

It is an amenable number.

105209 is a deficient number, since it is larger than the sum of its proper divisors (8107).

105209 is an equidigital number, since it uses as much as digits as its factorization.

105209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8106.

The product of its (nonzero) digits is 90, while the sum is 17.

The square root of 105209 is about 324.3593686022. The cubic root of 105209 is about 47.2082205829.

It can be divided in two parts, 105 and 209, that multiplied together give a triangular number (21945 = T₂₀₉).

The spelling of 105209 in words is "one hundred five thousand, two hundred nine".