645807044 has 6 divisors (see below), whose sum is σ = 1130162334. Its totient is φ = 322903520.

The previous prime is 645807011. The next prime is 645807047. The reversal of 645807044 is 440708546.

It can be written as a sum of positive squares in only one way, i.e., 374809600 + 270997444 = 19360^2 + 16462^2 .

It is a junction number, because it is equal to n+sod(n) for n = 645806989 and 645807007.

It is not an unprimeable number, because it can be changed into a prime (645807047) 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 as a sum of consecutive naturals, namely, 80725877 + ... + 80725884.

It is an arithmetic number, because the mean of its divisors is an integer number (188360389).

Almost surely, 2^645807044 is an apocalyptic number.

It is an amenable number.

645807044 is a deficient number, since it is larger than the sum of its proper divisors (484355290).

645807044 is a wasteful number, since it uses less digits than its factorization.

645807044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161451765 (or 161451763 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 38.

The square root of 645807044 is about 25412.7338946442. The cubic root of 645807044 is about 864.3724692213.

The spelling of 645807044 in words is "six hundred forty-five million, eight hundred seven thousand, forty-four".