640653517440 has 192 divisors, whose sum is σ = 2212681746600. Its totient is φ = 170808115200.

The previous prime is 640653517423. The next prime is 640653517523. The reversal of 640653517440 is 44715356046.

640653517440 is a `hidden beast` number, since 6 + 4 + 0 + 6 + 535 + 1 + 74 + 40 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 486656921664 + 153996595776 = 697608^2 + 392424^2 .

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (45).

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 23 ways as a sum of consecutive naturals, for example, 51655240 + ... + 51667640.

Almost surely, 2^640653517440 is an apocalyptic number.

640653517440 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 640653517440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1106340873300).

640653517440 is an abundant number, since it is smaller than the sum of its proper divisors (1572028229160).

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

640653517440 is a wasteful number, since it uses less digits than its factorization.

640653517440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21395 (or 21380 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 45.

The spelling of 640653517440 in words is "six hundred forty billion, six hundred fifty-three million, five hundred seventeen thousand, four hundred forty".