1666345 has 4 divisors (see below), whose sum is σ = 1999620. Its totient is φ = 1333072.

The previous prime is 1666339. The next prime is 1666351. The reversal of 1666345 is 5436661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5436661 = 733 ⋅7417.

It is an interprime number because it is at equal distance from previous prime (1666339) and next prime (1666351).

It can be written as a sum of positive squares in 2 ways, for example, as 440896 + 1225449 = 664^2 + 1107^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666345 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 166630 + ... + 166639.

It is an arithmetic number, because the mean of its divisors is an integer number (499905).

2^1666345 is an apocalyptic number.

It is an amenable number.

1666345 is a deficient number, since it is larger than the sum of its proper divisors (333275).

1666345 is an equidigital number, since it uses as much as digits as its factorization.

1666345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333274.

The product of its digits is 12960, while the sum is 31.

The square root of 1666345 is about 1290.8698617599. The cubic root of 1666345 is about 118.5554820988. Note that the first 3 decimals are identical.

The spelling of 1666345 in words is "one million, six hundred sixty-six thousand, three hundred forty-five".