645691297824 has 240 divisors, whose sum is σ = 1983789517248. Its totient is φ = 205637211648.

The previous prime is 645691297817. The next prime is 645691297829. The reversal of 645691297824 is 428792196546.

645691297824 is a `hidden beast` number, since 6 + 456 + 9 + 12 + 97 + 82 + 4 = 666.

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (645691297829) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 56450634 + ... + 56462070.

Almost surely, 2^645691297824 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 645691297824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (991894758624).

645691297824 is an abundant number, since it is smaller than the sum of its proper divisors (1338098219424).

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

645691297824 is a wasteful number, since it uses less digits than its factorization.

645691297824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12429 (or 12412 counting only the distinct ones).

The product of its digits is 52254720, while the sum is 63.

The spelling of 645691297824 in words is "six hundred forty-five billion, six hundred ninety-one million, two hundred ninety-seven thousand, eight hundred twenty-four".