6645812400 has 480 divisors, whose sum is σ = 25185888000. Its totient is φ = 1659709440.

The previous prime is 6645812377. The next prime is 6645812401. The reversal of 6645812400 is 42185466.

6645812400 is a `hidden beast` number, since 6 + 645 + 8 + 1 + 2 + 4 + 0 + 0 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (6645812401) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 28522684 + ... + 28522916.

It is an arithmetic number, because the mean of its divisors is an integer number (52470600).

Almost surely, 2^6645812400 is an apocalyptic number.

6645812400 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 6645812400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12592944000).

6645812400 is an abundant number, since it is smaller than the sum of its proper divisors (18540075600).

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

6645812400 is a wasteful number, since it uses less digits than its factorization.

6645812400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418 (or 401 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 6645812400 is about 81521.8522851389. The cubic root of 6645812400 is about 1880.1075462846.

Adding to 6645812400 its reverse (42185466), we get a palindrome (6687997866).

The spelling of 6645812400 in words is "six billion, six hundred forty-five million, eight hundred twelve thousand, four hundred".