1666397 has 2 divisors, whose sum is σ = 1666398. Its totient is φ = 1666396.

The previous prime is 1666393. The next prime is 1666403. The reversal of 1666397 is 7936661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1522756 + 143641 = 1234^2 + 379^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666397 - 2² = 1666393 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1666397.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666393) 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 as a sum of consecutive naturals, namely, 833198 + 833199.

It is an arithmetic number, because the mean of its divisors is an integer number (833199).

2^1666397 is an apocalyptic number.

It is an amenable number.

1666397 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666397 is an equidigital number, since it uses as much as digits as its factorization.

1666397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40824, while the sum is 38.

The square root of 1666397 is about 1290.8900030599. The cubic root of 1666397 is about 118.5567153010.

The spelling of 1666397 in words is "one million, six hundred sixty-six thousand, three hundred ninety-seven".