664779817440 has 480 divisors, whose sum is σ = 2429602560000. Its totient is φ = 171003571200.

The previous prime is 664779817433. The next prime is 664779817459. The reversal of 664779817440 is 44718977466.

664779817440 is a `hidden beast` number, since 6 + 6 + 47 + 79 + 81 + 7 + 440 = 666.

664779817440 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 (480).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 132980061 + ... + 132985059.

It is an arithmetic number, because the mean of its divisors is an integer number (5061672000).

Almost surely, 2^664779817440 is an apocalyptic number.

664779817440 is a gapful number since it is divisible by the number (60) 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 664779817440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1214801280000).

664779817440 is an abundant number, since it is smaller than the sum of its proper divisors (1764822742560).

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

664779817440 is a wasteful number, since it uses less digits than its factorization.

664779817440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5388 (or 5371 counting only the distinct ones).

The product of its (nonzero) digits is 56899584, while the sum is 63.

The spelling of 664779817440 in words is "six hundred sixty-four billion, seven hundred seventy-nine million, eight hundred seventeen thousand, four hundred forty".