1809904 has 40 divisors (see below), whose sum is σ = 3749760. Its totient is φ = 844800.

The previous prime is 1809901. The next prime is 1809911. The reversal of 1809904 is 4099081.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1809901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20292 + ... + 20380.

It is an arithmetic number, because the mean of its divisors is an integer number (93744).

2^1809904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1809904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1874880).

1809904 is an abundant number, since it is smaller than the sum of its proper divisors (1939856).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1809904 is a wasteful number, since it uses less digits than its factorization.

1809904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1809904 is about 1345.3267261153. The cubic root of 1809904 is about 121.8667361480.

It can be divided in two parts, 1809 and 904, that multiplied together give a triangular number (1635336 = T₁₈₀₈).

The spelling of 1809904 in words is "one million, eight hundred nine thousand, nine hundred four".