664537609728 has 320 divisors, whose sum is σ = 2033895536640. Its totient is φ = 214012108800.

The previous prime is 664537609699. The next prime is 664537609763. The reversal of 664537609728 is 827906735466.

664537609728 is a `hidden beast` number, since 6 + 6 + 4 + 537 + 6 + 0 + 97 + 2 + 8 = 666.

It is a super-2 number, since 2×664537609728² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 416115426 + ... + 416117022.

It is an arithmetic number, because the mean of its divisors is an integer number (6355923552).

Almost surely, 2^664537609728 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 664537609728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1016947768320).

664537609728 is an abundant number, since it is smaller than the sum of its proper divisors (1369357926912).

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

664537609728 is a wasteful number, since it uses less digits than its factorization.

664537609728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2626 (or 2604 counting only the distinct ones).

The product of its (nonzero) digits is 91445760, while the sum is 63.

The spelling of 664537609728 in words is "six hundred sixty-four billion, five hundred thirty-seven million, six hundred nine thousand, seven hundred twenty-eight".