6645819960 has 320 divisors, whose sum is σ = 24358229280. Its totient is φ = 1615334400.

The previous prime is 6645819953. The next prime is 6645819977. The reversal of 6645819960 is 699185466.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 6645819897 and 6645819906.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 3495010 + ... + 3496910.

Almost surely, 2^6645819960 is an apocalyptic number.

6645819960 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 6645819960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12179114640).

6645819960 is an abundant number, since it is smaller than the sum of its proper divisors (17712409320).

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

6645819960 is a wasteful number, since it uses less digits than its factorization.

6645819960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2020 (or 2007 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 54.

The square root of 6645819960 is about 81521.8986530613. The cubic root of 6645819960 is about 1880.1082591951.

It can be divided in two parts, 664581 and 9960, that added together give a triangular number (674541 = T₁₁₆₁).

The spelling of 6645819960 in words is "six billion, six hundred forty-five million, eight hundred nineteen thousand, nine hundred sixty".