381809 has 4 divisors (see below), whose sum is σ = 384000. Its totient is φ = 379620.

The previous prime is 381793. The next prime is 381817. The reversal of 381809 is 908183.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 381809 - 2⁴ = 381793 is a prime.

It is a super-2 number, since 2×381809² = 291556224962, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (381859) 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, 809 + ... + 1190.

It is an arithmetic number, because the mean of its divisors is an integer number (96000).

2³⁸¹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

381809 is a deficient number, since it is larger than the sum of its proper divisors (2191).

381809 is a wasteful number, since it uses less digits than its factorization.

381809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2190.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 381809 is about 617.9069509238. The cubic root of 381809 is about 72.5463199839.

The spelling of 381809 in words is "three hundred eighty-one thousand, eight hundred nine".