644985419040 has 144 divisors (see below), whose sum is σ = 2201627203776. Its totient is φ = 171948096000.

The previous prime is 644985419011. The next prime is 644985419063. The reversal of 644985419040 is 40914589446.

644985419040 is a `hidden beast` number, since 6 + 4 + 4 + 9 + 8 + 541 + 90 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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, 5254365 + ... + 5375715.

It is an arithmetic number, because the mean of its divisors is an integer number (15289077804).

Almost surely, 2^644985419040 is an apocalyptic number.

644985419040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644985419040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1100813601888).

644985419040 is an abundant number, since it is smaller than the sum of its proper divisors (1556641784736).

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

644985419040 is a wasteful number, since it uses less digits than its factorization.

644985419040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125063 (or 125052 counting only the distinct ones).

The product of its (nonzero) digits is 4976640, while the sum is 54.

The spelling of 644985419040 in words is "six hundred forty-four billion, nine hundred eighty-five million, four hundred nineteen thousand, forty".