640028321280 has 1280 divisors, whose sum is σ = 2514124800000. Its totient is φ = 153718456320.

The previous prime is 640028321263. The next prime is 640028321281. The reversal of 640028321280 is 82123820046.

640028321280 is a `hidden beast` number, since 640 + 0 + 2 + 8 + 3 + 2 + 1 + 2 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1280).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640028321281) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3216222621 + ... + 3216222819.

It is an arithmetic number, because the mean of its divisors is an integer number (1964160000).

Almost surely, 2^640028321280 is an apocalyptic number.

640028321280 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 640028321280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1257062400000).

640028321280 is an abundant number, since it is smaller than the sum of its proper divisors (1874096478720).

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

640028321280 is a wasteful number, since it uses less digits than its factorization.

640028321280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360 (or 338 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The spelling of 640028321280 in words is "six hundred forty billion, twenty-eight million, three hundred twenty-one thousand, two hundred eighty".