664481664 has 384 divisors, whose sum is σ = 2474438400. Its totient is φ = 171832320.

The previous prime is 664481651. The next prime is 664481689. The reversal of 664481664 is 466184466.

664481664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2927119 + ... + 2927345.

It is an arithmetic number, because the mean of its divisors is an integer number (6443850).

Almost surely, 2^664481664 is an apocalyptic number.

664481664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664481664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1237219200).

664481664 is an abundant number, since it is smaller than the sum of its proper divisors (1809956736).

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

664481664 is a wasteful number, since it uses less digits than its factorization.

664481664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279 (or 250 counting only the distinct ones).

The product of its digits is 663552, while the sum is 45.

The square root of 664481664 is about 25777.5418533265. The cubic root of 664481664 is about 872.6250323411.

The spelling of 664481664 in words is "six hundred sixty-four million, four hundred eighty-one thousand, six hundred sixty-four".