21811603968 has 640 divisors, whose sum is σ = 83217530880. Its totient is φ = 5474304000.

The previous prime is 21811603967. The next prime is 21811604011. The reversal of 21811603968 is 86930611812.

21811603968 is a `hidden beast` number, since 21 + 8 + 11 + 603 + 9 + 6 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (21811603967) 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, 32997558 + ... + 32998218.

It is an arithmetic number, because the mean of its divisors is an integer number (130027392).

Almost surely, 2^21811603968 is an apocalyptic number.

21811603968 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 21811603968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41608765440).

21811603968 is an abundant number, since it is smaller than the sum of its proper divisors (61405926912).

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

21811603968 is a wasteful number, since it uses less digits than its factorization.

21811603968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 737 (or 715 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The spelling of 21811603968 in words is "twenty-one billion, eight hundred eleven million, six hundred three thousand, nine hundred sixty-eight".