21241918656 has 224 divisors, whose sum is σ = 72826880000. Its totient is φ = 6068950272.

The previous prime is 21241918631. The next prime is 21241918669. The reversal of 21241918656 is 65681914212.

21241918656 is a `hidden beast` number, since 2 + 1 + 2 + 419 + 186 + 56 = 666.

It is a tau number, because it is divible by the number of its divisors (224).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 574785 + ... + 610623.

It is an arithmetic number, because the mean of its divisors is an integer number (325120000).

Almost surely, 2^21241918656 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 21241918656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36413440000).

21241918656 is an abundant number, since it is smaller than the sum of its proper divisors (51584961344).

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

21241918656 is an equidigital number, since it uses as much as digits as its factorization.

21241918656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35881 (or 35851 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The spelling of 21241918656 in words is "twenty-one billion, two hundred forty-one million, nine hundred eighteen thousand, six hundred fifty-six".