645840000 has 640 divisors, whose sum is σ = 2676643200. Its totient is φ = 152064000.

The previous prime is 645839993. The next prime is 645840007. The reversal of 645840000 is 48546.

645840000 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (645839993) and next prime (645840007).

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645840007) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 28079989 + ... + 28080011.

It is an arithmetic number, because the mean of its divisors is an integer number (4182255).

Almost surely, 2^645840000 is an apocalyptic number.

645840000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645840000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1338321600).

645840000 is an abundant number, since it is smaller than the sum of its proper divisors (2030803200).

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

645840000 is a wasteful number, since it uses less digits than its factorization.

645840000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 645840000 is about 25413.3823014568. The cubic root of 645840000 is about 864.3871721551.

Adding to 645840000 its reverse (48546), we get a palindrome (645888546).

The spelling of 645840000 in words is "six hundred forty-five million, eight hundred forty thousand".