816689 has 2 divisors, whose sum is σ = 816690. Its totient is φ = 816688.

The previous prime is 816667. The next prime is 816691. The reversal of 816689 is 986618.

816689 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 795664 + 21025 = 892^2 + 145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-816689 is a prime.

Together with 816691, it forms a pair of twin primes.

It is a Chen prime.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (816649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408344 + 408345.

It is an arithmetic number, because the mean of its divisors is an integer number (408345).

2⁸¹⁶⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

816689 is a deficient number, since it is larger than the sum of its proper divisors (1).

816689 is an equidigital number, since it uses as much as digits as its factorization.

816689 is an evil number, because the sum of its binary digits is even.

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

The square root of 816689 is about 903.7084706917. The cubic root of 816689 is about 93.4728681035.

The spelling of 816689 in words is "eight hundred sixteen thousand, six hundred eighty-nine".