640841 has 4 divisors (see below), whose sum is σ = 644292. Its totient is φ = 637392.

The previous prime is 640837. The next prime is 640847. The reversal of 640841 is 148046.

It is a happy number.

640841 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 633616 + 7225 = 796^2 + 85^2 .

It is a cyclic number.

It is not a de Polignac number, because 640841 - 2² = 640837 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640847) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1430 + ... + 1823.

It is an arithmetic number, because the mean of its divisors is an integer number (161073).

2⁶⁴⁰⁸⁴¹ is an apocalyptic number.

It is an amenable number.

640841 is a deficient number, since it is larger than the sum of its proper divisors (3451).

640841 is a wasteful number, since it uses less digits than its factorization.

640841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3450.

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

The square root of 640841 is about 800.5254524373. The cubic root of 640841 is about 86.2151185703.

Adding to 640841 its reverse (148046), we get a palindrome (788887).

The spelling of 640841 in words is "six hundred forty thousand, eight hundred forty-one".