1666688 has 32 divisors (see below), whose sum is σ = 3442500. Its totient is φ = 802816.

The previous prime is 1666657. The next prime is 1666711. The reversal of 1666688 is 8866661.

1666688 is nontrivially palindromic in base 7.

It can be written as a sum of positive squares in 2 ways, for example, as 1658944 + 7744 = 1288^2 + 88^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a plaindrome in base 10.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3488 + ... + 3936.

2^1666688 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 1666688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1721250).

1666688 is an abundant number, since it is smaller than the sum of its proper divisors (1775812).

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

1666688 is an equidigital number, since it uses as much as digits as its factorization.

1666688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492 (or 480 counting only the distinct ones).

The product of its digits is 82944, while the sum is 41.

The square root of 1666688 is about 1291.0027110738. The cubic root of 1666688 is about 118.5636160168.

The spelling of 1666688 in words is "one million, six hundred sixty-six thousand, six hundred eighty-eight".