1680729 has 4 divisors (see below), whose sum is σ = 2240976. Its totient is φ = 1120484.

The previous prime is 1680709. The next prime is 1680743. The reversal of 1680729 is 9270861.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9270861 = 3 ⋅3090287.

It is a cyclic number.

It is not a de Polignac number, because 1680729 - 2⁵ = 1680697 is a prime.

It is a d-powerful number, because it can be written as 1 + 6⁸ + 8³ + 0 + 7 + 2⁹ + 9² .

It is a D-number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1680729.

It is not an unprimeable number, because it can be changed into a prime (1680709) 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 3 ways as a sum of consecutive naturals, for example, 280119 + ... + 280124.

It is an arithmetic number, because the mean of its divisors is an integer number (560244).

2^1680729 is an apocalyptic number.

It is an amenable number.

1680729 is a deficient number, since it is larger than the sum of its proper divisors (560247).

1680729 is an equidigital number, since it uses as much as digits as its factorization.

1680729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 560246.

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 1680729 is about 1296.4293270364. The cubic root of 1680729 is about 118.8956314858.

It can be divided in two parts, 16807 and 29, that added together give a triangular number (16836 = T₁₈₃).

The spelling of 1680729 in words is "one million, six hundred eighty thousand, seven hundred twenty-nine".