645265666 has 16 divisors (see below), whose sum is σ = 973769400. Its totient is φ = 320681088.

The previous prime is 645265637. The next prime is 645265703. The reversal of 645265666 is 666562546.

645265666 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 561927025 + 83338641 = 23705^2 + 9129^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 499950 + ... + 501238.

Almost surely, 2^645265666 is an apocalyptic number.

645265666 is a deficient number, since it is larger than the sum of its proper divisors (328503734).

645265666 is a wasteful number, since it uses less digits than its factorization.

645265666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2613.

The product of its digits is 1555200, while the sum is 46.

The square root of 645265666 is about 25402.0799542085. The cubic root of 645265666 is about 864.1308681297.

The spelling of 645265666 in words is "six hundred forty-five million, two hundred sixty-five thousand, six hundred sixty-six".