640747680 has 288 divisors, whose sum is σ = 2228083200. Its totient is φ = 154583040.

The previous prime is 640747673. The next prime is 640747691. The reversal of 640747680 is 86747046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4300246 + ... + 4300394.

It is an arithmetic number, because the mean of its divisors is an integer number (7736400).

Almost surely, 2^640747680 is an apocalyptic number.

640747680 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 640747680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1114041600).

640747680 is an abundant number, since it is smaller than the sum of its proper divisors (1587335520).

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

640747680 is a wasteful number, since it uses less digits than its factorization.

640747680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232 (or 207 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 42.

The square root of 640747680 is about 25312.9942914701. The cubic root of 640747680 is about 862.1093345237.

The spelling of 640747680 in words is "six hundred forty million, seven hundred forty-seven thousand, six hundred eighty".