1665684 has 60 divisors (see below), whose sum is σ = 4482324. Its totient is φ = 539136.

The previous prime is 1665679. The next prime is 1665689. The reversal of 1665684 is 4865661.

It is an interprime number because it is at equal distance from previous prime (1665679) and next prime (1665689).

It can be written as a sum of positive squares in 2 ways, for example, as 980100 + 685584 = 990^2 + 828^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665689) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 17124 + ... + 17220.

2^1665684 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 1665684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2241162).

1665684 is an abundant number, since it is smaller than the sum of its proper divisors (2816640).

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

1665684 is a wasteful number, since it uses less digits than its factorization.

1665684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 155 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 1665684 is about 1290.6138074575. The cubic root of 1665684 is about 118.5398039654.

The spelling of 1665684 in words is "one million, six hundred sixty-five thousand, six hundred eighty-four".