261804 has 12 divisors (see below), whose sum is σ = 610904. Its totient is φ = 87264.

The previous prime is 261799. The next prime is 261823. The reversal of 261804 is 408162.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 10897 + ... + 10920.

2²⁶¹⁸⁰⁴ is an apocalyptic number.

It is an amenable number.

261804 is an abundant number, since it is smaller than the sum of its proper divisors (349100).

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

261804 is a wasteful number, since it uses less digits than its factorization.

261804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21824 (or 21822 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 261804 is about 511.6678610192. The cubic root of 261804 is about 63.9723187582.

Adding to 261804 its reverse (408162), we get a palindrome (669966).

It can be divided in two parts, 26 and 1804, that added together give a triangular number (1830 = T₆₀).

The spelling of 261804 in words is "two hundred sixty-one thousand, eight hundred four".