21816183816 has 256 divisors, whose sum is σ = 71164262400. Its totient is φ = 6062853888.

The previous prime is 21816183803. The next prime is 21816183821. The reversal of 21816183816 is 61838161812.

21816183816 is a `hidden beast` number, since 2 + 18 + 1 + 618 + 3 + 8 + 16 = 666.

It is a nude number because it is divisible by every one of its digits.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 19959366 + ... + 19960458.

It is an arithmetic number, because the mean of its divisors is an integer number (277985400).

Almost surely, 2^21816183816 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 21816183816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35582131200).

21816183816 is an abundant number, since it is smaller than the sum of its proper divisors (49348078584).

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

21816183816 is a wasteful number, since it uses less digits than its factorization.

21816183816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1465 (or 1455 counting only the distinct ones).

The product of its digits is 110592, while the sum is 45.

The spelling of 21816183816 in words is "twenty-one billion, eight hundred sixteen million, one hundred eighty-three thousand, eight hundred sixteen".