640064726784 has 360 divisors, whose sum is σ = 2192723140608. Its totient is φ = 181910292480.

The previous prime is 640064726761. The next prime is 640064726789. The reversal of 640064726784 is 487627460046.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 640064726784.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640064726789) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 27712489 + ... + 27735575.

Almost surely, 2^640064726784 is an apocalyptic number.

640064726784 is a gapful number since it is divisible by the number (64) 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 640064726784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1096361570304).

640064726784 is an abundant number, since it is smaller than the sum of its proper divisors (1552658413824).

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

640064726784 is a wasteful number, since it uses less digits than its factorization.

640064726784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23313 (or 23290 counting only the distinct ones).

The product of its (nonzero) digits is 10838016, while the sum is 54.

The spelling of 640064726784 in words is "six hundred forty billion, sixty-four million, seven hundred twenty-six thousand, seven hundred eighty-four".