640555044 has 12 divisors (see below), whose sum is σ = 1494628464. Its totient is φ = 213518344.

The previous prime is 640555031. The next prime is 640555061. The reversal of 640555044 is 440555046.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 640554996 and 640555014.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 26689782 + ... + 26689805.

It is an arithmetic number, because the mean of its divisors is an integer number (124552372).

Almost surely, 2^640555044 is an apocalyptic number.

It is an amenable number.

640555044 is an abundant number, since it is smaller than the sum of its proper divisors (854073420).

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

640555044 is a wasteful number, since it uses less digits than its factorization.

640555044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53379594 (or 53379592 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 33.

The square root of 640555044 is about 25309.1889241832. The cubic root of 640555044 is about 862.0229302887.

The spelling of 640555044 in words is "six hundred forty million, five hundred fifty-five thousand, forty-four".