644005003205 has 8 divisors (see below), whose sum is σ = 772824794904. Its totient is φ = 515191475200.

The previous prime is 644005003193. The next prime is 644005003219. The reversal of 644005003205 is 502300500446.

It can be written as a sum of positive squares in 4 ways, for example, as 59992664356 + 584012338849 = 244934^2 + 764207^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644005003205 - 2²² = 644000808901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1336676 + ... + 1753485.

It is an arithmetic number, because the mean of its divisors is an integer number (96603099363).

Almost surely, 2^644005003205 is an apocalyptic number.

It is an amenable number.

644005003205 is a deficient number, since it is larger than the sum of its proper divisors (128819791699).

644005003205 is a wasteful number, since it uses less digits than its factorization.

644005003205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3131847.

The product of its (nonzero) digits is 14400, while the sum is 29.

It can be divided in two parts, 64400 and 5003205, that added together give a palindrome (5067605).

The spelling of 644005003205 in words is "six hundred forty-four billion, five million, three thousand, two hundred five".