1666489 has 4 divisors (see below), whose sum is σ = 1818000. Its totient is φ = 1514980.

The previous prime is 1666487. The next prime is 1666499. The reversal of 1666489 is 9846661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9846661 = 11 ⋅895151.

It is a cyclic number.

It is not a de Polignac number, because 1666489 - 2¹ = 1666487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666481) 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, 75739 + ... + 75760.

It is an arithmetic number, because the mean of its divisors is an integer number (454500).

2^1666489 is an apocalyptic number.

It is an amenable number.

1666489 is a deficient number, since it is larger than the sum of its proper divisors (151511).

1666489 is a wasteful number, since it uses less digits than its factorization.

1666489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151510.

The product of its digits is 62208, while the sum is 40.

The square root of 1666489 is about 1290.9256368978. The cubic root of 1666489 is about 118.5588970574.

The spelling of 1666489 in words is "one million, six hundred sixty-six thousand, four hundred eighty-nine".