644665615216 has 40 divisors (see below), whose sum is σ = 1489537949184. Its totient is φ = 264272859840.

The previous prime is 644665615201. The next prime is 644665615241. The reversal of 644665615216 is 612516566446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 125126620 + ... + 125131771.

Almost surely, 2^644665615216 is an apocalyptic number.

It is an amenable number.

644665615216 is an abundant number, since it is smaller than the sum of its proper divisors (844872333968).

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

644665615216 is a wasteful number, since it uses less digits than its factorization.

644665615216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250258429 (or 250258423 counting only the distinct ones).

The product of its digits is 6220800, while the sum is 52.

The spelling of 644665615216 in words is "six hundred forty-four billion, six hundred sixty-five million, six hundred fifteen thousand, two hundred sixteen".