6645640500 has 144 divisors (see below), whose sum is σ = 21641518080. Its totient is φ = 1714968000.

The previous prime is 6645640489. The next prime is 6645640501. The reversal of 6645640500 is 50465466.

It is a happy number.

6645640500 is a `hidden beast` number, since 6 + 6 + 4 + 5 + 640 + 5 + 0 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6645640501) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 115681 + ... + 163319.

It is an arithmetic number, because the mean of its divisors is an integer number (150288320).

Almost surely, 2^6645640500 is an apocalyptic number.

6645640500 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 6645640500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10820759040).

6645640500 is an abundant number, since it is smaller than the sum of its proper divisors (14995877580).

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

6645640500 is a wasteful number, since it uses less digits than its factorization.

6645640500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47695 (or 47680 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

The square root of 6645640500 is about 81520.7979597845. The cubic root of 6645640500 is about 1880.0913359126.

The spelling of 6645640500 in words is "six billion, six hundred forty-five million, six hundred forty thousand, five hundred".