209081 has 4 divisors (see below), whose sum is σ = 210000. Its totient is φ = 208164.

The previous prime is 209071. The next prime is 209089. The reversal of 209081 is 180902.

209081 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 a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 209081 - 2¹⁰ = 208057 is a prime.

It is a super-2 number, since 2×209081² = 87429729122, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (209089) 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, 170 + ... + 668.

It is an arithmetic number, because the mean of its divisors is an integer number (52500).

2²⁰⁹⁰⁸¹ is an apocalyptic number.

It is an amenable number.

209081 is a deficient number, since it is larger than the sum of its proper divisors (919).

209081 is an equidigital number, since it uses as much as digits as its factorization.

209081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 918.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 209081 is about 457.2537588692. The cubic root of 209081 is about 59.3523869568.

Adding to 209081 its reverse (180902), we get a palindrome (389983).

The spelling of 209081 in words is "two hundred nine thousand, eighty-one".