664511379840 has 768 divisors, whose sum is σ = 2886385881600. Its totient is φ = 136848015360.

The previous prime is 664511379823. The next prime is 664511379863. The reversal of 664511379840 is 48973115466.

664511379840 is a `hidden beast` number, since 6 + 6 + 4 + 511 + 37 + 98 + 4 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 50111131 + ... + 50124389.

It is an arithmetic number, because the mean of its divisors is an integer number (3758314950).

Almost surely, 2^664511379840 is an apocalyptic number.

664511379840 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 664511379840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1443192940800).

664511379840 is an abundant number, since it is smaller than the sum of its proper divisors (2221874501760).

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

664511379840 is a wasteful number, since it uses less digits than its factorization.

664511379840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13415 (or 13400 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 54.

The spelling of 664511379840 in words is "six hundred sixty-four billion, five hundred eleven million, three hundred seventy-nine thousand, eight hundred forty".