1666404 has 36 divisors (see below), whose sum is σ = 4318860. Its totient is φ = 541440.

The previous prime is 1666403. The next prime is 1666409. The reversal of 1666404 is 4046661.

It can be written as a sum of positive squares in 2 ways, for example, as 108900 + 1557504 = 330^2 + 1248^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (1666403) 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 11 ways as a sum of consecutive naturals, for example, 912 + ... + 2040.

2^1666404 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 1666404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2159430).

1666404 is an abundant number, since it is smaller than the sum of its proper divisors (2652456).

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

1666404 is a wasteful number, since it uses less digits than its factorization.

1666404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1180 (or 1175 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 1666404 is about 1290.8927143648. The cubic root of 1666404 is about 118.5568813070.

The spelling of 1666404 in words is "one million, six hundred sixty-six thousand, four hundred four".