644574726432 has 480 divisors, whose sum is σ = 2335992607872. Its totient is φ = 169790017536.

The previous prime is 644574726427. The next prime is 644574726437. The reversal of 644574726432 is 234627475446.

644574726432 is a `hidden beast` number, since 6 + 4 + 4 + 574 + 7 + 2 + 64 + 3 + 2 = 666.

It is an interprime number because it is at equal distance from previous prime (644574726427) and next prime (644574726437).

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

It is not an unprimeable number, because it can be changed into a prime (644574726437) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 338003623 + ... + 338005529.

Almost surely, 2^644574726432 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 644574726432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1167996303936).

644574726432 is an abundant number, since it is smaller than the sum of its proper divisors (1691417881440).

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

644574726432 is a wasteful number, since it uses less digits than its factorization.

644574726432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3382 (or 3365 counting only the distinct ones).

The product of its digits is 27095040, while the sum is 54.

The spelling of 644574726432 in words is "six hundred forty-four billion, five hundred seventy-four million, seven hundred twenty-six thousand, four hundred thirty-two".