1728321 has 8 divisors (see below), whose sum is σ = 2633664. Its totient is φ = 987600.

The previous prime is 1728319. The next prime is 1728323. The reversal of 1728321 is 1238271.

It is an interprime number because it is at equal distance from previous prime (1728319) and next prime (1728323).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1728321 - 2¹ = 1728319 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

1728321 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1728291 and 1728300.

It is not an unprimeable number, because it can be changed into a prime (1728323) 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 in 7 ways as a sum of consecutive naturals, for example, 41130 + ... + 41171.

It is an arithmetic number, because the mean of its divisors is an integer number (329208).

2^1728321 is an apocalyptic number.

It is an amenable number.

1728321 is a deficient number, since it is larger than the sum of its proper divisors (905343).

1728321 is an equidigital number, since it uses as much as digits as its factorization.

1728321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82311.

The product of its digits is 672, while the sum is 24.

The square root of 1728321 is about 1314.6562288294. The cubic root of 1728321 is about 120.0074300955.

The spelling of 1728321 in words is "one million, seven hundred twenty-eight thousand, three hundred twenty-one".