640120320 has 560 divisors, whose sum is σ = 2683533600. Its totient is φ = 146313216.

The previous prime is 640120237. The next prime is 640120339. The reversal of 640120320 is 23021046.

It is a happy number.

640120320 is a `hidden beast` number, since 640 + 1 + 2 + 0 + 3 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (560).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 640120293 and 640120302.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 91445757 + ... + 91445763.

Almost surely, 2^640120320 is an apocalyptic number.

640120320 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 640120320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1341766800).

640120320 is an abundant number, since it is smaller than the sum of its proper divisors (2043413280).

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

640120320 is an frugal number, since it uses more digits than its factorization.

640120320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62 (or 17 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 640120320 is about 25300.5992023904. The cubic root of 640120320 is about 861.8278771251.

Adding to 640120320 its reverse (23021046), we get a palindrome (663141366).

The spelling of 640120320 in words is "six hundred forty million, one hundred twenty thousand, three hundred twenty".