644854065860 has 48 divisors (see below), whose sum is σ = 1399289106432. Its totient is φ = 249368803200.

The previous prime is 644854065839. The next prime is 644854065881. The reversal of 644854065860 is 68560458446.

It is an interprime number because it is at equal distance from previous prime (644854065839) and next prime (644854065881).

It is a junction number, because it is equal to n+sod(n) for n = 644854065796 and 644854065805.

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, 89654 + ... + 1139186.

It is an arithmetic number, because the mean of its divisors is an integer number (29151856384).

Almost surely, 2^644854065860 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644854065860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (699644553216).

644854065860 is an abundant number, since it is smaller than the sum of its proper divisors (754435040572).

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

644854065860 is a wasteful number, since it uses less digits than its factorization.

644854065860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1050564 (or 1050562 counting only the distinct ones).

The product of its (nonzero) digits is 22118400, while the sum is 56.

The spelling of 644854065860 in words is "six hundred forty-four billion, eight hundred fifty-four million, sixty-five thousand, eight hundred sixty".