21818818368 has 196 divisors, whose sum is σ = 68736430980. Its totient is φ = 6844870656.

The previous prime is 21818818339. The next prime is 21818818387. The reversal of 21818818368 is 86381881812.

It can be written as a sum of positive squares in 2 ways, for example, as 8112965184 + 13705853184 = 90072^2 + 117072^2 .

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

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

It is a congruent number.

It is an unprimeable number.

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 27 ways as a sum of consecutive naturals, for example, 779398 + ... + 806906.

Almost surely, 2^21818818368 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 21818818368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34368215490).

21818818368 is an abundant number, since it is smaller than the sum of its proper divisors (46917612612).

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

21818818368 is an equidigital number, since it uses as much as digits as its factorization.

21818818368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27556 (or 27531 counting only the distinct ones).

The product of its digits is 1179648, while the sum is 54.

The spelling of 21818818368 in words is "twenty-one billion, eight hundred eighteen million, eight hundred eighteen thousand, three hundred sixty-eight".