645406800 has 120 divisors (see below), whose sum is σ = 2078066400. Its totient is φ = 171225600.

The previous prime is 645406781. The next prime is 645406831. The reversal of 645406800 is 8604546.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 251926 + ... + 254474.

It is an arithmetic number, because the mean of its divisors is an integer number (17317220).

Almost surely, 2^645406800 is an apocalyptic number.

645406800 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 645406800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1039033200).

645406800 is an abundant number, since it is smaller than the sum of its proper divisors (1432659600).

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

645406800 is a wasteful number, since it uses less digits than its factorization.

645406800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2781 (or 2770 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 33.

The square root of 645406800 is about 25404.8578031840. The cubic root of 645406800 is about 864.1938651048.

The spelling of 645406800 in words is "six hundred forty-five million, four hundred six thousand, eight hundred".