664761718333440 has 4480 divisors, whose sum is σ = 3038545499996160. Its totient is φ = 135307022303232.

The previous prime is 664761718333411. The next prime is 664761718333463. The reversal of 664761718333440 is 44333817167466.

664761718333440 is a `hidden beast` number, since 6 + 6 + 4 + 7 + 6 + 1 + 7 + 183 + 3 + 3 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (4480).

It is a super-2 number, since 2×664761718333440² (a number of 30 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 1121014701784 + ... + 1121014702376.

It is an arithmetic number, because the mean of its divisors is an integer number (678246763392).

Almost surely, 2^{664761718333440} is an apocalyptic number.

664761718333440 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 664761718333440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1519272749998080).

664761718333440 is an abundant number, since it is smaller than the sum of its proper divisors (2373783781662720).

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

664761718333440 is a wasteful number, since it uses less digits than its factorization.

664761718333440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782 (or 749 counting only the distinct ones).

The product of its (nonzero) digits is 146313216, while the sum is 63.

The spelling of 664761718333440 in words is "six hundred sixty-four trillion, seven hundred sixty-one billion, seven hundred eighteen million, three hundred thirty-three thousand, four hundred forty".