645537626768 has 20 divisors (see below), whose sum is σ = 1255180154028. Its totient is φ = 321620167680.

The previous prime is 645537626761. The next prime is 645537626813. The reversal of 645537626768 is 867626735546.

It can be written as a sum of positive squares in 2 ways, for example, as 548026322944 + 97511303824 = 740288^2 + 312268^2 .

It is not an unprimeable number, because it can be changed into a prime (645537626761) 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 3 ways as a sum of consecutive naturals, for example, 71785721 + ... + 71794712.

Almost surely, 2^645537626768 is an apocalyptic number.

It is an amenable number.

645537626768 is a deficient number, since it is larger than the sum of its proper divisors (609642527260).

645537626768 is a wasteful number, since it uses less digits than its factorization.

645537626768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143580722 (or 143580716 counting only the distinct ones).

The product of its digits is 304819200, while the sum is 65.

The spelling of 645537626768 in words is "six hundred forty-five billion, five hundred thirty-seven million, six hundred twenty-six thousand, seven hundred sixty-eight".