2165904 has 90 divisors (see below), whose sum is σ = 6637410. Its totient is φ = 658944.

The previous prime is 2165903. The next prime is 2165921. The reversal of 2165904 is 4095612.

2165904 is a `hidden beast` number, since 2 + 1 + 659 + 0 + 4 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 57600 + 2108304 = 240^2 + 1452^2 .

It is a super-2 number, since 2×2165904² = 9382280274432, which contains 22 as substring.

It is a nialpdrome in base 12.

It is a zygodrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (2165903) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 24292 + ... + 24380.

It is an arithmetic number, because the mean of its divisors is an integer number (73749).

2^2165904 is an apocalyptic number.

2165904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2165904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3318705).

2165904 is an abundant number, since it is smaller than the sum of its proper divisors (4471506).

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

2165904 is a wasteful number, since it uses less digits than its factorization.

2165904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 2165904 is about 1471.7010566008. The cubic root of 2165904 is about 129.3837500208.

The spelling of 2165904 in words is "two million, one hundred sixty-five thousand, nine hundred four".