644869376 has 18 divisors (see below), whose sum is σ = 1287220242. Its totient is φ = 322434560.

The previous prime is 644869373. The next prime is 644869399. The reversal of 644869376 is 673968446.

644869376 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 556960000 + 87909376 = 23600^2 + 9376^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644869373) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1259255 + ... + 1259766.

Almost surely, 2^644869376 is an apocalyptic number.

It is an amenable number.

644869376 is a deficient number, since it is larger than the sum of its proper divisors (642350866).

644869376 is an equidigital number, since it uses as much as digits as its factorization.

644869376 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2519037 (or 2519023 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 53.

The square root of 644869376 is about 25394.2784106972. The cubic root of 644869376 is about 863.9539298709.

The spelling of 644869376 in words is "six hundred forty-four million, eight hundred sixty-nine thousand, three hundred seventy-six".