645791328 has 288 divisors, whose sum is σ = 2319250752. Its totient is φ = 165888000.

The previous prime is 645791299. The next prime is 645791347. The reversal of 645791328 is 823197546.

645791328 is a `hidden beast` number, since 64 + 579 + 13 + 2 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1074228 + ... + 1074828.

It is an arithmetic number, because the mean of its divisors is an integer number (8052954).

Almost surely, 2^645791328 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 645791328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1159625376).

645791328 is an abundant number, since it is smaller than the sum of its proper divisors (1673459424).

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

645791328 is a wasteful number, since it uses less digits than its factorization.

645791328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 667 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 645791328 is about 25412.4246777044. The cubic root of 645791328 is about 864.3654575357.

The spelling of 645791328 in words is "six hundred forty-five million, seven hundred ninety-one thousand, three hundred twenty-eight".