645811760 has 80 divisors (see below), whose sum is σ = 1642394880. Its totient is φ = 234213120.

The previous prime is 645811753. The next prime is 645811769. The reversal of 645811760 is 67118546.

645811760 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (645811769) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 441911 + ... + 443369.

It is an arithmetic number, because the mean of its divisors is an integer number (20529936).

Almost surely, 2^645811760 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 645811760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (821197440).

645811760 is an abundant number, since it is smaller than the sum of its proper divisors (996583120).

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

645811760 is a wasteful number, since it uses less digits than its factorization.

645811760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1986 (or 1980 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 645811760 is about 25412.8266826026. The cubic root of 645811760 is about 864.3745732402.

The spelling of 645811760 in words is "six hundred forty-five million, eight hundred eleven thousand, seven hundred sixty".