19878566400 has 1440 divisors, whose sum is σ = 93087042048. Its totient is φ = 4080844800.

The previous prime is 19878566359. The next prime is 19878566401. The reversal of 19878566400 is 466587891.

19878566400 is a `hidden beast` number, since 1 + 9 + 8 + 78 + 566 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1440).

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

It is not an unprimeable number, because it can be changed into a prime (19878566401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 239500759 + ... + 239500841.

Almost surely, 2^19878566400 is an apocalyptic number.

19878566400 is a gapful number since it is divisible by the number (10) 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 19878566400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46543521024).

19878566400 is an abundant number, since it is smaller than the sum of its proper divisors (73208475648).

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

19878566400 is an equidigital number, since it uses as much as digits as its factorization.

19878566400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144 (or 111 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 19878566400 in words is "nineteen billion, eight hundred seventy-eight million, five hundred sixty-six thousand, four hundred".