8121578400 has 720 divisors, whose sum is σ = 33030885888. Its totient is φ = 1928448000.

The previous prime is 8121578393. The next prime is 8121578401. The reversal of 8121578400 is 48751218.

8121578400 is a `hidden beast` number, since 81 + 2 + 1 + 578 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

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 (8121578401) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 26114245 + ... + 26114555.

Almost surely, 2^8121578400 is an apocalyptic number.

8121578400 is a gapful number since it is divisible by the number (80) 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 8121578400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16515442944).

8121578400 is an abundant number, since it is smaller than the sum of its proper divisors (24909307488).

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

8121578400 is a wasteful number, since it uses less digits than its factorization.

8121578400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 387 (or 365 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

The square root of 8121578400 is about 90119.8002660902. The cubic root of 8121578400 is about 2010.0806383331.

The spelling of 8121578400 in words is "eight billion, one hundred twenty-one million, five hundred seventy-eight thousand, four hundred".