645563520 has 384 divisors, whose sum is σ = 2646483840. Its totient is φ = 147308544.

The previous prime is 645563489. The next prime is 645563543. The reversal of 645563520 is 25365546.

It is a happy number.

645563520 is a `hidden beast` number, since 6 + 45 + 563 + 52 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1088344 + ... + 1088936.

It is an arithmetic number, because the mean of its divisors is an integer number (6891885).

Almost surely, 2^645563520 is an apocalyptic number.

645563520 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 645563520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1323241920).

645563520 is an abundant number, since it is smaller than the sum of its proper divisors (2000920320).

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

645563520 is an equidigital number, since it uses as much as digits as its factorization.

645563520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 634 (or 610 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 36.

The square root of 645563520 is about 25407.9420654251. The cubic root of 645563520 is about 864.2638083311.

The spelling of 645563520 in words is "six hundred forty-five million, five hundred sixty-three thousand, five hundred twenty".