646645 has 8 divisors (see below), whose sum is σ = 809856. Its totient is φ = 494736.

The previous prime is 646643. The next prime is 646669. The reversal of 646645 is 546646.

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

It is a cyclic number.

It is not a de Polignac number, because 646645 - 2¹ = 646643 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646643) 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, 2697 + ... + 2926.

It is an arithmetic number, because the mean of its divisors is an integer number (101232).

2⁶⁴⁶⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

646645 is a deficient number, since it is larger than the sum of its proper divisors (163211).

646645 is a wasteful number, since it uses less digits than its factorization.

646645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5651.

The product of its digits is 17280, while the sum is 31.

The square root of 646645 is about 804.1424003247. The cubic root of 646645 is about 86.4746158266.

Subtracting from 646645 its reverse (546646), we obtain a palindrome (99999).

The spelling of 646645 in words is "six hundred forty-six thousand, six hundred forty-five".