181909009 has 4 divisors (see below), whose sum is σ = 182389360. Its totient is φ = 181428660.

The previous prime is 181908997. The next prime is 181909033. The reversal of 181909009 is 900909181.

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 an emirpimes, since its reverse is a distinct semiprime: 900909181 = 991 ⋅909091.

It is a cyclic number.

It is not a de Polignac number, because 181909009 - 2²³ = 173520401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181909069) 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, 239607 + ... + 240364.

It is an arithmetic number, because the mean of its divisors is an integer number (45597340).

Almost surely, 2^181909009 is an apocalyptic number.

It is an amenable number.

181909009 is a deficient number, since it is larger than the sum of its proper divisors (480351).

181909009 is an equidigital number, since it uses as much as digits as its factorization.

181909009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 480350.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 181909009 is about 13487.3647907959. The cubic root of 181909009 is about 566.6106535561.

The spelling of 181909009 in words is "one hundred eighty-one million, nine hundred nine thousand, nine".