645363216 has 135 divisors (see below), whose sum is σ = 1896523239. Its totient is φ = 204857856.

The previous prime is 645363211. The next prime is 645363241. The reversal of 645363216 is 612363546.

The square root of 645363216 is 25404.

It is a perfect power (a square), and thus also a powerful number.

645363216 is a `hidden beast` number, since 6 + 4 + 5 + 3 + 632 + 16 = 666.

645363216 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 5475600 + 639887616 = 2340^2 + 25296^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (645363211) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 8840556 + ... + 8840628.

Almost surely, 2^645363216 is an apocalyptic number.

645363216 is the 25404-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645363216

645363216 is an abundant number, since it is smaller than the sum of its proper divisors (1251160023).

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

645363216 is a wasteful number, since it uses less digits than its factorization.

645363216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218 (or 107 counting only the distinct ones).

The product of its digits is 77760, while the sum is 36.

The cubic root of 645363216 is about 864.1744118064.

Multiplying 645363216 by its sum of digits (36), we get a square (23233075776 = 152424²).

645363216 divided by its sum of digits (36) gives a square (17926756 = 4234²).

The spelling of 645363216 in words is "six hundred forty-five million, three hundred sixty-three thousand, two hundred sixteen".