1680809 has 4 divisors (see below), whose sum is σ = 1810116. Its totient is φ = 1551504.

The previous prime is 1680803. The next prime is 1680821. The reversal of 1680809 is 9080861.

1680809 = T₅₀₂ + T₅₀₃ + ... + T₅₁₄.

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

It can be written as a sum of positive squares in 2 ways, for example, as 426409 + 1254400 = 653^2 + 1120^2 .

It is a cyclic number.

It is not a de Polignac number, because 1680809 - 2⁴ = 1680793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1680803) 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, 64634 + ... + 64659.

It is an arithmetic number, because the mean of its divisors is an integer number (452529).

2^1680809 is an apocalyptic number.

It is an amenable number.

1680809 is a deficient number, since it is larger than the sum of its proper divisors (129307).

1680809 is a wasteful number, since it uses less digits than its factorization.

1680809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129306.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 1680809 is about 1296.4601806457. The cubic root of 1680809 is about 118.8975178696.

The spelling of 1680809 in words is "one million, six hundred eighty thousand, eight hundred nine".