1728217 has 4 divisors (see below), whose sum is σ = 1731636. Its totient is φ = 1724800.

The previous prime is 1728193. The next prime is 1728229. The reversal of 1728217 is 7128271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7128271 = 157 ⋅45403.

It can be written as a sum of positive squares in 2 ways, for example, as 373321 + 1354896 = 611^2 + 1164^2 .

It is a cyclic number.

It is not a de Polignac number, because 1728217 - 2¹⁹ = 1203929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1728247) 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 in 3 ways as a sum of consecutive naturals, for example, 784 + ... + 2017.

It is an arithmetic number, because the mean of its divisors is an integer number (432909).

2^1728217 is an apocalyptic number.

It is an amenable number.

1728217 is a deficient number, since it is larger than the sum of its proper divisors (3419).

1728217 is an equidigital number, since it uses as much as digits as its factorization.

1728217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3418.

The product of its digits is 1568, while the sum is 28.

The square root of 1728217 is about 1314.6166741678. The cubic root of 1728217 is about 120.0050229379.

The spelling of 1728217 in words is "one million, seven hundred twenty-eight thousand, two hundred seventeen".