21761843208 has 256 divisors, whose sum is σ = 69835530240. Its totient is φ = 5504716800.

The previous prime is 21761843189. The next prime is 21761843237. The reversal of 21761843208 is 80234816712.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 21761843208.

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, 4004253 + ... + 4009683.

It is an arithmetic number, because the mean of its divisors is an integer number (272795040).

Almost surely, 2^21761843208 is an apocalyptic number.

21761843208 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 21761843208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34917765120).

21761843208 is an abundant number, since it is smaller than the sum of its proper divisors (48073687032).

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

21761843208 is a wasteful number, since it uses less digits than its factorization.

21761843208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5548 (or 5544 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 42.

The spelling of 21761843208 in words is "twenty-one billion, seven hundred sixty-one million, eight hundred forty-three thousand, two hundred eight".