645258816 has 84 divisors (see below), whose sum is σ = 1913343900. Its totient is φ = 207664128.

The previous prime is 645258781. The next prime is 645258833. The reversal of 645258816 is 618852546.

645258816 is a `hidden beast` number, since 6 + 4 + 52 + 588 + 16 = 666.

645258816 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 2 ways, for example, as 141705216 + 503553600 = 11904^2 + 22440^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2611 + ... + 36018.

Almost surely, 2^645258816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645258816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (956671950).

645258816 is an abundant number, since it is smaller than the sum of its proper divisors (1268085084).

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

645258816 is a wasteful number, since it uses less digits than its factorization.

645258816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38676 (or 38663 counting only the distinct ones).

The product of its digits is 460800, while the sum is 45.

The square root of 645258816 is about 25401.9451223720. The cubic root of 645258816 is about 864.1278103104.

The spelling of 645258816 in words is "six hundred forty-five million, two hundred fifty-eight thousand, eight hundred sixteen".