641705840 has 20 divisors (see below), whose sum is σ = 1491966264. Its totient is φ = 256682304.

The previous prime is 641705839. The next prime is 641705849. The reversal of 641705840 is 48507146.

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 641705840.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641705849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4010582 + ... + 4010741.

Almost surely, 2^641705840 is an apocalyptic number.

It is an amenable number.

641705840 is an abundant number, since it is smaller than the sum of its proper divisors (850260424).

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

641705840 is a wasteful number, since it uses less digits than its factorization.

641705840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8021336 (or 8021330 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 641705840 is about 25331.9134689822. The cubic root of 641705840 is about 862.5388469516.

The spelling of 641705840 in words is "six hundred forty-one million, seven hundred five thousand, eight hundred forty".