641344640 has 32 divisors (see below), whose sum is σ = 1533216060. Its totient is φ = 256537600.

The previous prime is 641344631. The next prime is 641344661. The reversal of 641344640 is 46443146.

641344640 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 581002816 + 60341824 = 24104^2 + 7768^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a super-2 number, since 2×641344640² = 822645894513459200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 641344597 and 641344606.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 500411 + ... + 501690.

Almost surely, 2^641344640 is an apocalyptic number.

It is an amenable number.

641344640 is an abundant number, since it is smaller than the sum of its proper divisors (891871420).

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

641344640 is a wasteful number, since it uses less digits than its factorization.

641344640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1002120 (or 1002108 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 32.

The square root of 641344640 is about 25324.7831185185. The cubic root of 641344640 is about 862.3769828051.

Adding to 641344640 its reverse (46443146), we get a palindrome (687787786).

The spelling of 641344640 in words is "six hundred forty-one million, three hundred forty-four thousand, six hundred forty".