1728521 has 4 divisors (see below), whose sum is σ = 1731600. Its totient is φ = 1725444.

The previous prime is 1728511. The next prime is 1728527. The reversal of 1728521 is 1258271.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1728521 - 2⁶ = 1728457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1728527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 431 + ... + 1908.

It is an arithmetic number, because the mean of its divisors is an integer number (432900).

2^1728521 is an apocalyptic number.

It is an amenable number.

1728521 is a deficient number, since it is larger than the sum of its proper divisors (3079).

1728521 is an equidigital number, since it uses as much as digits as its factorization.

1728521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3078.

The product of its digits is 1120, while the sum is 26.

The square root of 1728521 is about 1314.7322921416. The cubic root of 1728521 is about 120.0120589733.

The spelling of 1728521 in words is "one million, seven hundred twenty-eight thousand, five hundred twenty-one".