645744440880 has 960 divisors, whose sum is σ = 2859538406400. Its totient is φ = 126516142080.

The previous prime is 645744440867. The next prime is 645744440903. The reversal of 645744440880 is 88044447546.

645744440880 is a `hidden beast` number, since 64 + 574 + 4 + 4 + 4 + 0 + 8 + 8 + 0 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 241218102 + ... + 241220778.

It is an arithmetic number, because the mean of its divisors is an integer number (2978685840).

Almost surely, 2^645744440880 is an apocalyptic number.

645744440880 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 645744440880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1429769203200).

645744440880 is an abundant number, since it is smaller than the sum of its proper divisors (2213793965520).

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

645744440880 is a wasteful number, since it uses less digits than its factorization.

645744440880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2962 (or 2953 counting only the distinct ones).

The product of its (nonzero) digits is 13762560, while the sum is 54.

The spelling of 645744440880 in words is "six hundred forty-five billion, seven hundred forty-four million, four hundred forty thousand, eight hundred eighty".