646647 has 8 divisors (see below), whose sum is σ = 865920. Its totient is φ = 429240.

The previous prime is 646643. The next prime is 646669. The reversal of 646647 is 746646.

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

It is not a de Polignac number, because 646647 - 2² = 646643 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.

646647 is a lucky 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, 1072 + ... + 1562.

It is an arithmetic number, because the mean of its divisors is an integer number (108240).

2⁶⁴⁶⁶⁴⁷ is an apocalyptic number.

646647 is a deficient number, since it is larger than the sum of its proper divisors (219273).

646647 is a wasteful number, since it uses less digits than its factorization.

646647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 933.

The product of its digits is 24192, while the sum is 33.

The square root of 646647 is about 804.1436438846. The cubic root of 646647 is about 86.4747049786.

Subtracting 646647 from its reverse (746646), we obtain a palindrome (99999).

The spelling of 646647 in words is "six hundred forty-six thousand, six hundred forty-seven".