1666657 has 2 divisors, whose sum is σ = 1666658. Its totient is φ = 1666656.

The previous prime is 1666627. The next prime is 1666711. The reversal of 1666657 is 7566661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1245456 + 421201 = 1116^2 + 649^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666657 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666607) by changing a digit.

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 as a sum of consecutive naturals, namely, 833328 + 833329.

It is an arithmetic number, because the mean of its divisors is an integer number (833329).

2^1666657 is an apocalyptic number.

It is an amenable number.

1666657 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666657 is an equidigital number, since it uses as much as digits as its factorization.

1666657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 37.

The square root of 1666657 is about 1290.9907048465. The cubic root of 1666657 is about 118.5628809272.

The spelling of 1666657 in words is "one million, six hundred sixty-six thousand, six hundred fifty-seven".