647664 has 40 divisors (see below), whose sum is σ = 1702272. Its totient is φ = 212160.

The previous prime is 647663. The next prime is 647687. The reversal of 647664 is 466746.

647664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 647664.

It is not an unprimeable number, because it can be changed into a prime (647663) 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, 4879 + ... + 5009.

2⁶⁴⁷⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 647664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (851136).

647664 is an abundant number, since it is smaller than the sum of its proper divisors (1054608).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

647664 is a wasteful number, since it uses less digits than its factorization.

647664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245 (or 239 counting only the distinct ones).

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

The square root of 647664 is about 804.7757451613. The cubic root of 647664 is about 86.5200149704.

The spelling of 647664 in words is "six hundred forty-seven thousand, six hundred sixty-four".