645633565 has 16 divisors (see below), whose sum is σ = 821518848. Its totient is φ = 485422336.

The previous prime is 645633553. The next prime is 645633581. The reversal of 645633565 is 565336546.

It is a cyclic number.

It is not a de Polignac number, because 645633565 - 2¹⁹ = 645109277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 58044 + ... + 68266.

It is an arithmetic number, because the mean of its divisors is an integer number (51344928).

Almost surely, 2^645633565 is an apocalyptic number.

It is an amenable number.

645633565 is a deficient number, since it is larger than the sum of its proper divisors (175885283).

645633565 is a wasteful number, since it uses less digits than its factorization.

645633565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10988.

The product of its digits is 972000, while the sum is 43.

The square root of 645633565 is about 25409.3204356197. The cubic root of 645633565 is about 864.2950653478.

The spelling of 645633565 in words is "six hundred forty-five million, six hundred thirty-three thousand, five hundred sixty-five".