21306055680 has 528 divisors, whose sum is σ = 90879332544. Its totient is φ = 4494458880.

The previous prime is 21306055619. The next prime is 21306055697. The reversal of 21306055680 is 8655060312.

21306055680 is a `hidden beast` number, since 2 + 1 + 30 + 60 + 5 + 568 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4190740 + ... + 4195820.

It is an arithmetic number, because the mean of its divisors is an integer number (172119948).

Almost surely, 2^21306055680 is an apocalyptic number.

21306055680 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 21306055680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45439666272).

21306055680 is an abundant number, since it is smaller than the sum of its proper divisors (69573276864).

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

21306055680 is a wasteful number, since it uses less digits than its factorization.

21306055680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5132 (or 5111 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The spelling of 21306055680 in words is "twenty-one billion, three hundred six million, fifty-five thousand, six hundred eighty".