1728689 has 2 divisors, whose sum is σ = 1728690. Its totient is φ = 1728688.

The previous prime is 1728659. The next prime is 1728691. The reversal of 1728689 is 9868271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1575025 + 153664 = 1255^2 + 392^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1728689 is a prime.

Together with 1728691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1728659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 864344 + 864345.

It is an arithmetic number, because the mean of its divisors is an integer number (864345).

2^1728689 is an apocalyptic number.

It is an amenable number.

1728689 is a deficient number, since it is larger than the sum of its proper divisors (1).

1728689 is an equidigital number, since it uses as much as digits as its factorization.

1728689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 41.

The square root of 1728689 is about 1314.7961819233. The cubic root of 1728689 is about 120.0159469548.

The spelling of 1728689 in words is "one million, seven hundred twenty-eight thousand, six hundred eighty-nine".