1666549 has 4 divisors (see below), whose sum is σ = 1669536. Its totient is φ = 1663564.

The previous prime is 1666541. The next prime is 1666559. The reversal of 1666549 is 9456661.

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: 9456661 = 19 ⋅497719.

It is a cyclic number.

It is not a de Polignac number, because 1666549 - 2³ = 1666541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 379 + ... + 1864.

It is an arithmetic number, because the mean of its divisors is an integer number (417384).

2^1666549 is an apocalyptic number.

It is an amenable number.

1666549 is a deficient number, since it is larger than the sum of its proper divisors (2987).

1666549 is an equidigital number, since it uses as much as digits as its factorization.

1666549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2986.

The product of its digits is 38880, while the sum is 37.

The square root of 1666549 is about 1290.9488758274. The cubic root of 1666549 is about 118.5603198988.

The spelling of 1666549 in words is "one million, six hundred sixty-six thousand, five hundred forty-nine".