1728009 has 12 divisors (see below), whose sum is σ = 2522052. Its totient is φ = 1140000.

The previous prime is 1727989. The next prime is 1728017. The reversal of 1728009 is 9008271.

It can be written as a sum of positive squares in 2 ways, for example, as 944784 + 783225 = 972^2 + 885^2 .

It is not a de Polignac number, because 1728009 - 2⁷ = 1727881 is a prime.

1728009 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1728019) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42 + ... + 1859.

It is an arithmetic number, because the mean of its divisors is an integer number (210171).

2^1728009 is an apocalyptic number.

It is an amenable number.

1728009 is a deficient number, since it is larger than the sum of its proper divisors (794043).

1728009 is a wasteful number, since it uses less digits than its factorization.

1728009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2008 (or 2005 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 1728009 is about 1314.5375612739. The cubic root of 1728009 is about 120.0002083330. Note that the first 3 decimals are identical.

The spelling of 1728009 in words is "one million, seven hundred twenty-eight thousand, nine".