1680691 has 4 divisors (see below), whose sum is σ = 1683352. Its totient is φ = 1678032.

The previous prime is 1680689. The next prime is 1680697. The reversal of 1680691 is 1960861.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1680691 - 2¹ = 1680689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1680697) 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, 220 + ... + 1846.

It is an arithmetic number, because the mean of its divisors is an integer number (420838).

2^1680691 is an apocalyptic number.

1680691 is a deficient number, since it is larger than the sum of its proper divisors (2661).

1680691 is a wasteful number, since it uses less digits than its factorization.

1680691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2660.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1680691 is about 1296.4146713147. The cubic root of 1680691 is about 118.8947354326.

The spelling of 1680691 in words is "one million, six hundred eighty thousand, six hundred ninety-one".