640389888 has 180 divisors, whose sum is σ = 1936546920. Its totient is φ = 210456576.

The previous prime is 640389887. The next prime is 640389901. The reversal of 640389888 is 888983046.

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

It is not an unprimeable number, because it can be changed into a prime (640389887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1845331 + ... + 1845677.

It is an arithmetic number, because the mean of its divisors is an integer number (10758594).

Almost surely, 2^640389888 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 640389888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (968273460).

640389888 is an abundant number, since it is smaller than the sum of its proper divisors (1296157032).

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

640389888 is an equidigital number, since it uses as much as digits as its factorization.

640389888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464 (or 441 counting only the distinct ones).

The product of its (nonzero) digits is 2654208, while the sum is 54.

The square root of 640389888 is about 25305.9259463075. The cubic root of 640389888 is about 861.9488380370.

The spelling of 640389888 in words is "six hundred forty million, three hundred eighty-nine thousand, eight hundred eighty-eight".