641840 has 40 divisors (see below), whose sum is σ = 1526688. Its totient is φ = 250880.

The previous prime is 641833. The next prime is 641843. The reversal of 641840 is 48146.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (641843) by changing a digit.

641840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5624 + ... + 5736.

2⁶⁴¹⁸⁴⁰ 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 641840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (763344).

641840 is an abundant number, since it is smaller than the sum of its proper divisors (884848).

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

641840 is a wasteful number, since it uses less digits than its factorization.

641840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 197 (or 191 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 641840 is about 801.1491746236. The cubic root of 641840 is about 86.2598952450.

Adding to 641840 its reverse (48146), we get a palindrome (689986).

The spelling of 641840 in words is "six hundred forty-one thousand, eight hundred forty".