640740320 has 96 divisors (see below), whose sum is σ = 1682765280. Its totient is φ = 228567040.

The previous prime is 640740313. The next prime is 640740337. The reversal of 640740320 is 23047046.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 640740320.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 89846 + ... + 96714.

It is an arithmetic number, because the mean of its divisors is an integer number (17528805).

Almost surely, 2^640740320 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640740320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (841382640).

640740320 is an abundant number, since it is smaller than the sum of its proper divisors (1042024960).

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

640740320 is a wasteful number, since it uses less digits than its factorization.

640740320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6948 (or 6940 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 26.

The square root of 640740320 is about 25312.8489111755. The cubic root of 640740320 is about 862.1060336149.

Adding to 640740320 its reverse (23047046), we get a palindrome (663787366).

The spelling of 640740320 in words is "six hundred forty million, seven hundred forty thousand, three hundred twenty".