1728375421 has 4 divisors (see below), whose sum is σ = 1760986332. Its totient is φ = 1695764512.

The previous prime is 1728375401. The next prime is 1728375427. The reversal of 1728375421 is 1245738271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1245738271 = 1361 ⋅915311.

It can be written as a sum of positive squares in 2 ways, for example, as 762036025 + 966339396 = 27605^2 + 31086^2 .

It is a cyclic number.

It is not a de Polignac number, because 1728375421 - 2⁷ = 1728375293 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1728375427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16305376 + ... + 16305481.

It is an arithmetic number, because the mean of its divisors is an integer number (440246583).

Almost surely, 2^1728375421 is an apocalyptic number.

It is an amenable number.

1728375421 is a deficient number, since it is larger than the sum of its proper divisors (32610911).

1728375421 is an equidigital number, since it uses as much as digits as its factorization.

1728375421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32610910.

The product of its digits is 94080, while the sum is 40.

The square root of 1728375421 is about 41573.7347492380. The cubic root of 1728375421 is about 1200.0868967166.

The spelling of 1728375421 in words is "one billion, seven hundred twenty-eight million, three hundred seventy-five thousand, four hundred twenty-one".