1680689 has 2 divisors, whose sum is σ = 1680690. Its totient is φ = 1680688.

The previous prime is 1680659. The next prime is 1680697. The reversal of 1680689 is 9860861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1311025 + 369664 = 1145^2 + 608^2 .

It is a cyclic number.

It is not a de Polignac number, because 1680689 - 2¹² = 1676593 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1680659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840344 + 840345.

It is an arithmetic number, because the mean of its divisors is an integer number (840345).

2^1680689 is an apocalyptic number.

It is an amenable number.

1680689 is a deficient number, since it is larger than the sum of its proper divisors (1).

1680689 is an equidigital number, since it uses as much as digits as its factorization.

1680689 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 1680689 is about 1296.4138999563. The cubic root of 1680689 is about 118.8946882715.

The spelling of 1680689 in words is "one million, six hundred eighty thousand, six hundred eighty-nine".