640849 has 16 divisors (see below), whose sum is σ = 777600. Its totient is φ = 520960.

The previous prime is 640847. The next prime is 640853. The reversal of 640849 is 948046.

640849 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640849 - 2¹ = 640847 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 640849.

It is a congruent 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 15 ways as a sum of consecutive naturals, for example, 4227 + ... + 4375.

It is an arithmetic number, because the mean of its divisors is an integer number (48600).

2⁶⁴⁰⁸⁴⁹ is an apocalyptic number.

It is an amenable number.

640849 is a deficient number, since it is larger than the sum of its proper divisors (136751).

640849 is a wasteful number, since it uses less digits than its factorization.

640849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 640849 is about 800.5304491398. The cubic root of 640849 is about 86.2154773270.

The spelling of 640849 in words is "six hundred forty thousand, eight hundred forty-nine".