644533464384 has 224 divisors, whose sum is σ = 1935224455680. Its totient is φ = 212937984000.

The previous prime is 644533464371. The next prime is 644533464469. The reversal of 644533464384 is 483464335446.

644533464384 is a `hidden beast` number, since 6 + 44 + 533 + 4 + 64 + 3 + 8 + 4 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 644533464384.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15796009 + ... + 15836759.

Almost surely, 2^644533464384 is an apocalyptic number.

644533464384 is a gapful number since it is divisible by the number (64) 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 644533464384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (967612227840).

644533464384 is an abundant number, since it is smaller than the sum of its proper divisors (1290690991296).

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

644533464384 is an equidigital number, since it uses as much as digits as its factorization.

644533464384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40897 (or 40869 counting only the distinct ones).

The product of its digits is 39813120, while the sum is 54.

The spelling of 644533464384 in words is "six hundred forty-four billion, five hundred thirty-three million, four hundred sixty-four thousand, three hundred eighty-four".