644628688680 has 64 divisors (see below), whose sum is σ = 2035669550400. Its totient is φ = 162853562880.

The previous prime is 644628688673. The next prime is 644628688709. The reversal of 644628688680 is 86886826446.

644628688680 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644628688680² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 141363661 + ... + 141368220.

It is an arithmetic number, because the mean of its divisors is an integer number (31807336725).

Almost surely, 2^644628688680 is an apocalyptic number.

644628688680 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644628688680 is an abundant number, since it is smaller than the sum of its proper divisors (1391040861720).

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

644628688680 is a wasteful number, since it uses less digits than its factorization.

644628688680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282731914 (or 282731910 counting only the distinct ones).

The product of its (nonzero) digits is 169869312, while the sum is 66.

The spelling of 644628688680 in words is "six hundred forty-four billion, six hundred twenty-eight million, six hundred eighty-eight thousand, six hundred eighty".