641868640 has 288 divisors, whose sum is σ = 1930521600. Its totient is φ = 200309760.

The previous prime is 641868599. The next prime is 641868641. The reversal of 641868640 is 46868146.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641868641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4617691 + ... + 4617829.

It is an arithmetic number, because the mean of its divisors is an integer number (6703200).

Almost surely, 2^641868640 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 641868640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (965260800).

641868640 is an abundant number, since it is smaller than the sum of its proper divisors (1288652960).

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

641868640 is a wasteful number, since it uses less digits than its factorization.

641868640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218 (or 203 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 43.

The square root of 641868640 is about 25335.1266031966. The cubic root of 641868640 is about 862.6117824735.

The spelling of 641868640 in words is "six hundred forty-one million, eight hundred sixty-eight thousand, six hundred forty".