21685044215808 has 1152 divisors, whose sum is σ = 69923872658640. Its totient is φ = 6468623400960.

The previous prime is 21685044215801. The next prime is 21685044215831. The reversal of 21685044215808 is 80851244058612.

It is a happy number.

21685044215808 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 50 + 4 + 4 + 2 + 1 + 580 + 8 = 666.

21685044215808 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (1152).

It is a super-2 number, since 2×21685044215808² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21685044215801) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 223557156816 + ... + 223557156912.

Almost surely, 2^{21685044215808} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21685044215808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34961936329320).

21685044215808 is an abundant number, since it is smaller than the sum of its proper divisors (48238828442832).

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

21685044215808 is an equidigital number, since it uses as much as digits as its factorization.

21685044215808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 4915200, while the sum is 54.

The spelling of 21685044215808 in words is "twenty-one trillion, six hundred eighty-five billion, forty-four million, two hundred fifteen thousand, eight hundred eight".