21878404471872 has 196 divisors, whose sum is σ = 70099790978700. Its totient is φ = 6731816573952.

The previous prime is 21878404471841. The next prime is 21878404471873. The reversal of 21878404471872 is 27817440487812.

It is a happy number.

21878404471872 is a `hidden beast` number, since 2 + 1 + 8 + 7 + 8 + 4 + 0 + 447 + 187 + 2 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 8922551340096 + 12955853131776 = 2987064^2 + 3599424^2 .

It is not an unprimeable number, because it can be changed into a prime (21878404471873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 17429247 + ... + 18642302.

Almost surely, 2^{21878404471872} is an apocalyptic number.

It is an amenable number.

21878404471872 is an abundant number, since it is smaller than the sum of its proper divisors (48221386506828).

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

21878404471872 is an equidigital number, since it uses as much as digits as its factorization.

21878404471872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36071592 (or 36071567 counting only the distinct ones).

The product of its (nonzero) digits is 44957696, while the sum is 63.

The spelling of 21878404471872 in words is "twenty-one trillion, eight hundred seventy-eight billion, four hundred four million, four hundred seventy-one thousand, eight hundred seventy-two".