1666559 has 2 divisors, whose sum is σ = 1666560. Its totient is φ = 1666558.

The previous prime is 1666541. The next prime is 1666589. The reversal of 1666559 is 9556661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666559 - 2⁸ = 1666303 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833279 + 833280.

It is an arithmetic number, because the mean of its divisors is an integer number (833280).

2^1666559 is an apocalyptic number.

1666559 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666559 is an equidigital number, since it uses as much as digits as its factorization.

1666559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48600, while the sum is 38.

The square root of 1666559 is about 1290.9527489416. The cubic root of 1666559 is about 118.5605570357.

The spelling of 1666559 in words is "one million, six hundred sixty-six thousand, five hundred fifty-nine".