664620640 has 96 divisors (see below), whose sum is σ = 1626809184. Its totient is φ = 256389120.

The previous prime is 664620631. The next prime is 664620667. The reversal of 664620640 is 46026466.

664620640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×664620640² = 883441190228019200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 664620596 and 664620605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 775092 + ... + 775948.

It is an arithmetic number, because the mean of its divisors is an integer number (16945929).

Almost surely, 2^664620640 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 664620640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (813404592).

664620640 is an abundant number, since it is smaller than the sum of its proper divisors (962188544).

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

664620640 is a wasteful number, since it uses less digits than its factorization.

664620640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1040 (or 1032 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 664620640 is about 25780.2373922352. The cubic root of 664620640 is about 872.6858644600.

The spelling of 664620640 in words is "six hundred sixty-four million, six hundred twenty thousand, six hundred forty".