641696640 has 256 divisors, whose sum is σ = 2253726720. Its totient is φ = 154312704.

The previous prime is 641696579. The next prime is 641696669. The reversal of 641696640 is 46696146.

It is a junction number, because it is equal to n+sod(n) for n = 641696592 and 641696601.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1172847 + ... + 1173393.

It is an arithmetic number, because the mean of its divisors is an integer number (8803620).

Almost surely, 2^641696640 is an apocalyptic number.

641696640 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 641696640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1126863360).

641696640 is an abundant number, since it is smaller than the sum of its proper divisors (1612030080).

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

641696640 is a wasteful number, since it uses less digits than its factorization.

641696640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 629 (or 617 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 42.

The square root of 641696640 is about 25331.7318792064. The cubic root of 641696640 is about 862.5347249199.

The spelling of 641696640 in words is "six hundred forty-one million, six hundred ninety-six thousand, six hundred forty".