645827840 has 144 divisors (see below), whose sum is σ = 1805260800. Its totient is φ = 221276160.

The previous prime is 645827839. The next prime is 645827873. The reversal of 645827840 is 48728546.

It is a junction number, because it is equal to n+sod(n) for n = 645827791 and 645827800.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 438305 + ... + 439775.

Almost surely, 2^645827840 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 645827840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (902630400).

645827840 is an abundant number, since it is smaller than the sum of its proper divisors (1159432960).

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

645827840 is an equidigital number, since it uses as much as digits as its factorization.

645827840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1513 (or 1485 counting only the distinct ones).

The product of its (nonzero) digits is 430080, while the sum is 44.

The square root of 645827840 is about 25413.1430563006. The cubic root of 645827840 is about 864.3817471716.

The spelling of 645827840 in words is "six hundred forty-five million, eight hundred twenty-seven thousand, eight hundred forty".