1666859 has 4 divisors (see below), whose sum is σ = 1669920. Its totient is φ = 1663800.

The previous prime is 1666853. The next prime is 1666871. The reversal of 1666859 is 9586661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1666859 - 2⁴ = 1666843 is a prime.

It is a super-3 number, since 3×1666859³ = 13893697777125233337, which contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 467 + ... + 1884.

It is an arithmetic number, because the mean of its divisors is an integer number (417480).

2^1666859 is an apocalyptic number.

1666859 is a deficient number, since it is larger than the sum of its proper divisors (3061).

1666859 is an equidigital number, since it uses as much as digits as its factorization.

1666859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3060.

The product of its digits is 77760, while the sum is 41.

The square root of 1666859 is about 1291.0689369666. The cubic root of 1666859 is about 118.5676707019.

The spelling of 1666859 in words is "one million, six hundred sixty-six thousand, eight hundred fifty-nine".