645888 has 54 divisors (see below), whose sum is σ = 1780324. Its totient is φ = 207872.

The previous prime is 645877. The next prime is 645889. The reversal of 645888 is 888546.

It is not an unprimeable number, because it can be changed into a prime (645889) by changing a digit.

645888 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22258 + ... + 22286.

2⁶⁴⁵⁸⁸⁸ 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 645888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (890162).

645888 is an abundant number, since it is smaller than the sum of its proper divisors (1134436).

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

645888 is an equidigital number, since it uses as much as digits as its factorization.

645888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77 (or 34 counting only the distinct ones).

The product of its digits is 61440, while the sum is 39.

The square root of 645888 is about 803.6715747120. The cubic root of 645888 is about 86.4408585899.

The spelling of 645888 in words is "six hundred forty-five thousand, eight hundred eighty-eight".