644518312 has 8 divisors (see below), whose sum is σ = 1208471850. Its totient is φ = 322259152.

The previous prime is 644518307. The next prime is 644518313. The reversal of 644518312 is 213815446.

It can be written as a sum of positive squares in only one way, i.e., 489913956 + 154604356 = 22134^2 + 12434^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (644518313) 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 as a sum of consecutive naturals, namely, 40282387 + ... + 40282402.

Almost surely, 2^644518312 is an apocalyptic number.

It is an amenable number.

644518312 is a deficient number, since it is larger than the sum of its proper divisors (563953538).

644518312 is a wasteful number, since it uses less digits than its factorization.

644518312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80564795 (or 80564791 counting only the distinct ones).

The product of its digits is 23040, while the sum is 34.

The square root of 644518312 is about 25387.3652039750. The cubic root of 644518312 is about 863.7971238627.

The spelling of 644518312 in words is "six hundred forty-four million, five hundred eighteen thousand, three hundred twelve".