644056523431776 has 4608 divisors, whose sum is σ = 2712039922335744. Its totient is φ = 145441308672000.

The previous prime is 644056523431729. The next prime is 644056523431787. The reversal of 644056523431776 is 677134325650446.

644056523431776 is a `hidden beast` number, since 6 + 4 + 4 + 0 + 5 + 6 + 523 + 4 + 31 + 7 + 76 = 666.

It is a super-2 number, since 2×644056523431776² (a number of 30 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 767 ways as a sum of consecutive naturals, for example, 523197825081 + ... + 523197826311.

It is an arithmetic number, because the mean of its divisors is an integer number (588550330368).

Almost surely, 2^{644056523431776} 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 644056523431776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1356019961167872).

644056523431776 is an abundant number, since it is smaller than the sum of its proper divisors (2067983398903968).

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

644056523431776 is a wasteful number, since it uses less digits than its factorization.

644056523431776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408 (or 1388 counting only the distinct ones).

The product of its (nonzero) digits is 304819200, while the sum is 63.

The spelling of 644056523431776 in words is "six hundred forty-four trillion, fifty-six billion, five hundred twenty-three million, four hundred thirty-one thousand, seven hundred seventy-six".