644785596 has 240 divisors, whose sum is σ = 2185666560. Its totient is φ = 160963200.

The previous prime is 644785591. The next prime is 644785601. The reversal of 644785596 is 695587446.

644785596 is a `hidden beast` number, since 6 + 4 + 47 + 8 + 5 + 596 = 666.

It is an interprime number because it is at equal distance from previous prime (644785591) and next prime (644785601).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644785591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 559621 + ... + 560771.

It is an arithmetic number, because the mean of its divisors is an integer number (9106944).

Almost surely, 2^644785596 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 644785596, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1092833280).

644785596 is an abundant number, since it is smaller than the sum of its proper divisors (1540880964).

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

644785596 is a wasteful number, since it uses less digits than its factorization.

644785596 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1206 (or 1195 counting only the distinct ones).

The product of its digits is 7257600, while the sum is 54.

The square root of 644785596 is about 25392.6287729333. The cubic root of 644785596 is about 863.9165139240.

The spelling of 644785596 in words is "six hundred forty-four million, seven hundred eighty-five thousand, five hundred ninety-six".