1666686 has 24 divisors (see below), whose sum is σ = 3878280. Its totient is φ = 476112.

The previous prime is 1666657. The next prime is 1666711. The reversal of 1666686 is 6866661.

1666686 = 644² + 645² + ... + 647².

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2541 + ... + 3128.

It is an arithmetic number, because the mean of its divisors is an integer number (161595).

2^1666686 is an apocalyptic number.

1666686 is an abundant number, since it is smaller than the sum of its proper divisors (2211594).

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

1666686 is a wasteful number, since it uses less digits than its factorization.

1666686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5688 (or 5681 counting only the distinct ones).

The product of its digits is 62208, while the sum is 39.

The square root of 1666686 is about 1291.0019364819. The cubic root of 1666686 is about 118.5635685919.

The spelling of 1666686 in words is "one million, six hundred sixty-six thousand, six hundred eighty-six".