165561804 has 18 divisors (see below), whose sum is σ = 418503540. Its totient is φ = 55187256.

The previous prime is 165561787. The next prime is 165561811. The reversal of 165561804 is 408165561.

165561804 is a `hidden beast` number, since 16 + 5 + 561 + 80 + 4 = 666.

165561804 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 4598939 = 165561804 / (1 + 6 + 5 + 5 + 6 + 1 + 8 + 0 + 4).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2299434 + ... + 2299505.

Almost surely, 2^165561804 is an apocalyptic number.

It is an amenable number.

165561804 is an abundant number, since it is smaller than the sum of its proper divisors (252941736).

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

165561804 is a wasteful number, since it uses less digits than its factorization.

165561804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4598949 (or 4598944 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 165561804 is about 12867.0821867275. The cubic root of 165561804 is about 549.1024523378.

The spelling of 165561804 in words is "one hundred sixty-five million, five hundred sixty-one thousand, eight hundred four".