644003140 has 36 divisors (see below), whose sum is σ = 1486535148. Its totient is φ = 234182080.

The previous prime is 644003123. The next prime is 644003141. The reversal of 644003140 is 41300446.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 200732224 + 443270916 = 14168^2 + 21054^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (644003141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 130639 + ... + 135478.

It is an arithmetic number, because the mean of its divisors is an integer number (41292643).

Almost surely, 2^644003140 is an apocalyptic number.

It is an amenable number.

644003140 is an abundant number, since it is smaller than the sum of its proper divisors (842532008).

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

644003140 is a wasteful number, since it uses less digits than its factorization.

644003140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266148 (or 266135 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 644003140 is about 25377.2169474905. The cubic root of 644003140 is about 863.5669143650.

Adding to 644003140 its reverse (41300446), we get a palindrome (685303586).

The spelling of 644003140 in words is "six hundred forty-four million, three thousand, one hundred forty".