644443540516660 has 72 divisors (see below), whose sum is σ = 1386279194428800. Its totient is φ = 251642763934848.

The previous prime is 644443540516649. The next prime is 644443540516679. The reversal of 644443540516660 is 66615045344446.

644443540516660 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 644443540516595 and 644443540516604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17641912 + ... + 40001551.

It is an arithmetic number, because the mean of its divisors is an integer number (19253877700400).

Almost surely, 2^{644443540516660} is an apocalyptic number.

It is an amenable number.

644443540516660 is an abundant number, since it is smaller than the sum of its proper divisors (741835653912140).

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

644443540516660 is a wasteful number, since it uses less digits than its factorization.

644443540516660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57643777 (or 57643722 counting only the distinct ones).

The product of its (nonzero) digits is 99532800, while the sum is 58.

The spelling of 644443540516660 in words is "six hundred forty-four trillion, four hundred forty-three billion, five hundred forty million, five hundred sixteen thousand, six hundred sixty".