641905 has 12 divisors (see below), whose sum is σ = 847476. Its totient is φ = 466400.

The previous prime is 641897. The next prime is 641909. The reversal of 641905 is 509146.

It can be written as a sum of positive squares in 2 ways, for example, as 327184 + 314721 = 572^2 + 561^2 .

It is not a de Polignac number, because 641905 - 2³ = 641897 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 641905.

It is not an unprimeable number, because it can be changed into a prime (641909) 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 11 ways as a sum of consecutive naturals, for example, 75 + ... + 1135.

It is an arithmetic number, because the mean of its divisors is an integer number (70623).

2⁶⁴¹⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

641905 is a deficient number, since it is larger than the sum of its proper divisors (205571).

641905 is a wasteful number, since it uses less digits than its factorization.

641905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1088 (or 1077 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 641905 is about 801.1897403237. The cubic root of 641905 is about 86.2628070319.

The spelling of 641905 in words is "six hundred forty-one thousand, nine hundred five".