1728991 has 4 divisors (see below), whose sum is σ = 1886184. Its totient is φ = 1571800.

The previous prime is 1728983. The next prime is 1728997. The reversal of 1728991 is 1998271.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1728991 - 2³ = 1728983 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1728991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1728997) 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, 78580 + ... + 78601.

It is an arithmetic number, because the mean of its divisors is an integer number (471546).

2^1728991 is an apocalyptic number.

1728991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1728991 is a deficient number, since it is larger than the sum of its proper divisors (157193).

1728991 is a wasteful number, since it uses less digits than its factorization.

1728991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157192.

The product of its digits is 9072, while the sum is 37.

The square root of 1728991 is about 1314.9110236058. The cubic root of 1728991 is about 120.0229354309.

The spelling of 1728991 in words is "one million, seven hundred twenty-eight thousand, nine hundred ninety-one".