644965216 has 48 divisors (see below), whose sum is σ = 1452971520. Its totient is φ = 276071040.

The previous prime is 644965187. The next prime is 644965253. The reversal of 644965216 is 612569446.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 274575 + ... + 276913.

It is an arithmetic number, because the mean of its divisors is an integer number (30270240).

Almost surely, 2^644965216 is an apocalyptic number.

It is an amenable number.

644965216 is an abundant number, since it is smaller than the sum of its proper divisors (808006304).

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

644965216 is a wasteful number, since it uses less digits than its factorization.

644965216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3587 (or 3579 counting only the distinct ones).

The product of its digits is 311040, while the sum is 43.

The square root of 644965216 is about 25396.1653798364. The cubic root of 644965216 is about 863.9967278111.

The spelling of 644965216 in words is "six hundred forty-four million, nine hundred sixty-five thousand, two hundred sixteen".