644264313840 has 240 divisors, whose sum is σ = 2475189452736. Its totient is φ = 147115008000.

The previous prime is 644264313829. The next prime is 644264313853. The reversal of 644264313840 is 48313462446.

644264313840 is a `hidden beast` number, since 6 + 4 + 4 + 264 + 3 + 1 + 384 + 0 = 666.

644264313840 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5083240 + ... + 5208440.

Almost surely, 2^644264313840 is an apocalyptic number.

644264313840 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 644264313840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1237594726368).

644264313840 is an abundant number, since it is smaller than the sum of its proper divisors (1830925138896).

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

644264313840 is a wasteful number, since it uses less digits than its factorization.

644264313840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126248 (or 126239 counting only the distinct ones).

The product of its (nonzero) digits is 1327104, while the sum is 45.

The spelling of 644264313840 in words is "six hundred forty-four billion, two hundred sixty-four million, three hundred thirteen thousand, eight hundred forty".