644275386720 has 2016 divisors, whose sum is σ = 2967272028000. Its totient is φ = 130929426432.

The previous prime is 644275386709. The next prime is 644275386757. The reversal of 644275386720 is 27683572446.

644275386720 is a `hidden beast` number, since 6 + 4 + 4 + 27 + 538 + 67 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (2016).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 335 ways as a sum of consecutive naturals, for example, 1846061106 + ... + 1846061454.

It is an arithmetic number, because the mean of its divisors is an integer number (1471861125).

Almost surely, 2^644275386720 is an apocalyptic number.

644275386720 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 644275386720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1483636014000).

644275386720 is an abundant number, since it is smaller than the sum of its proper divisors (2322996641280).

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

644275386720 is a wasteful number, since it uses less digits than its factorization.

644275386720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432 (or 402 counting only the distinct ones).

The product of its (nonzero) digits is 13547520, while the sum is 54.

The spelling of 644275386720 in words is "six hundred forty-four billion, two hundred seventy-five million, three hundred eighty-six thousand, seven hundred twenty".