641984640 has 256 divisors, whose sum is σ = 2260483200. Its totient is φ = 153681920.

The previous prime is 641984639. The next prime is 641984647. The reversal of 641984640 is 46489146.

It is a junction number, because it is equal to n+sod(n) for n = 641984592 and 641984601.

It is not an unprimeable number, because it can be changed into a prime (641984647) 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 31 ways as a sum of consecutive naturals, for example, 2386426 + ... + 2386694.

Almost surely, 2^641984640 is an apocalyptic number.

641984640 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 641984640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1130241600).

641984640 is an abundant number, since it is smaller than the sum of its proper divisors (1618498560).

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

641984640 is a wasteful number, since it uses less digits than its factorization.

641984640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415 (or 403 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 42.

The square root of 641984640 is about 25337.4158114043. The cubic root of 641984640 is about 862.6637437489.

The spelling of 641984640 in words is "six hundred forty-one million, nine hundred eighty-four thousand, six hundred forty".