646809 has 8 divisors (see below), whose sum is σ = 868800. Its totient is φ = 428016.

The previous prime is 646781. The next prime is 646823. The reversal of 646809 is 908646.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 646809 - 2¹⁵ = 614041 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax 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 646809.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646809.

It is not an unprimeable number, because it can be changed into a prime (646859) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 277 + ... + 1170.

It is an arithmetic number, because the mean of its divisors is an integer number (108600).

2⁶⁴⁶⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

646809 is a deficient number, since it is larger than the sum of its proper divisors (221991).

646809 is a wasteful number, since it uses less digits than its factorization.

646809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1599.

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 646809 is about 804.2443658491. The cubic root of 646809 is about 86.4819256789.

The spelling of 646809 in words is "six hundred forty-six thousand, eight hundred nine".