641909664 has 384 divisors, whose sum is σ = 2253484800. Its totient is φ = 175472640.

The previous prime is 641909663. The next prime is 641909669. The reversal of 641909664 is 466909146.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641909663) 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 63 ways as a sum of consecutive naturals, for example, 4685404 + ... + 4685540.

It is an arithmetic number, because the mean of its divisors is an integer number (5868450).

Almost surely, 2^641909664 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 641909664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1126742400).

641909664 is an abundant number, since it is smaller than the sum of its proper divisors (1611575136).

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

641909664 is a wasteful number, since it uses less digits than its factorization.

641909664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The square root of 641909664 is about 25335.9362171600. The cubic root of 641909664 is about 862.6301595627.

The spelling of 641909664 in words is "six hundred forty-one million, nine hundred nine thousand, six hundred sixty-four".