21656242080 has 768 divisors, whose sum is σ = 86459788800. Its totient is φ = 5016453120.

The previous prime is 21656242051. The next prime is 21656242093. The reversal of 21656242080 is 8024265612.

It is a happy number.

21656242080 is a `hidden beast` number, since 2 + 1 + 6 + 5 + 624 + 20 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 191648104 + ... + 191648216.

It is an arithmetic number, because the mean of its divisors is an integer number (112577850).

Almost surely, 2^21656242080 is an apocalyptic number.

21656242080 is a gapful number since it is divisible by the number (20) 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 21656242080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43229894400).

21656242080 is an abundant number, since it is smaller than the sum of its proper divisors (64803546720).

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

21656242080 is a wasteful number, since it uses less digits than its factorization.

21656242080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The spelling of 21656242080 in words is "twenty-one billion, six hundred fifty-six million, two hundred forty-two thousand, eighty".