645913564840 has 32 divisors (see below), whose sum is σ = 1454081613480. Its totient is φ = 258227453952.

The previous prime is 645913564837. The next prime is 645913564847. The reversal of 645913564840 is 48465319546.

645913564840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 490316451076 + 155597113764 = 700226^2 + 394458^2 .

It is not an unprimeable number, because it can be changed into a prime (645913564847) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4235769 + ... + 4385608.

Almost surely, 2^645913564840 is an apocalyptic number.

It is an amenable number.

645913564840 is an abundant number, since it is smaller than the sum of its proper divisors (808168048640).

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

645913564840 is a wasteful number, since it uses less digits than its factorization.

645913564840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8623261 (or 8623257 counting only the distinct ones).

The product of its (nonzero) digits is 12441600, while the sum is 55.

The spelling of 645913564840 in words is "six hundred forty-five billion, nine hundred thirteen million, five hundred sixty-four thousand, eight hundred forty".