21811359108 has 192 divisors, whose sum is σ = 67805337600. Its totient is φ = 5282703360.

The previous prime is 21811359107. The next prime is 21811359109. The reversal of 21811359108 is 80195311812.

It is an interprime number because it is at equal distance from previous prime (21811359107) and next prime (21811359109).

It is a super-2 number, since 2×21811359108² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21811359107) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1705803 + ... + 1718541.

It is an arithmetic number, because the mean of its divisors is an integer number (353152800).

Almost surely, 2^21811359108 is an apocalyptic number.

21811359108 is a gapful number since it is divisible by the number (28) 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 21811359108, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33902668800).

21811359108 is an abundant number, since it is smaller than the sum of its proper divisors (45993978492).

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

21811359108 is a wasteful number, since it uses less digits than its factorization.

21811359108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12890 (or 12888 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 39.

The spelling of 21811359108 in words is "twenty-one billion, eight hundred eleven million, three hundred fifty-nine thousand, one hundred eight".