331809 has 4 divisors (see below), whose sum is σ = 442416. Its totient is φ = 221204.

The previous prime is 331801. The next prime is 331819. The reversal of 331809 is 908133.

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: 908133 = 3 ⋅302711.

It is a cyclic number.

It is not a de Polignac number, because 331809 - 2³ = 331801 is a prime.

It is a super-2 number, since 2×331809² = 220194424962, which contains 22 as substring.

It is a D-number.

331809 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 331809.

It is not an unprimeable number, because it can be changed into a prime (331801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55299 + ... + 55304.

It is an arithmetic number, because the mean of its divisors is an integer number (110604).

2³³¹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

331809 is a deficient number, since it is larger than the sum of its proper divisors (110607).

331809 is a wasteful number, since it uses less digits than its factorization.

331809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110606.

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 331809 is about 576.0286451211. The cubic root of 331809 is about 69.2302745454.

The spelling of 331809 in words is "three hundred thirty-one thousand, eight hundred nine".