21809668608 has 400 divisors, whose sum is σ = 80132162880. Its totient is φ = 5751005184.

The previous prime is 21809668589. The next prime is 21809668619. The reversal of 21809668608 is 80686690812.

It is a happy number.

21809668608 is a `hidden beast` number, since 21 + 8 + 0 + 9 + 6 + 6 + 8 + 608 = 666.

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

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 39 ways as a sum of consecutive naturals, for example, 3771063 + ... + 3776841.

Almost surely, 2^21809668608 is an apocalyptic number.

21809668608 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 21809668608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40066081440).

21809668608 is an abundant number, since it is smaller than the sum of its proper divisors (58322494272).

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

21809668608 is an equidigital number, since it uses as much as digits as its factorization.

21809668608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5829 (or 5804 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 54.

The spelling of 21809668608 in words is "twenty-one billion, eight hundred nine million, six hundred sixty-eight thousand, six hundred eight".