21056534550 has 192 divisors, whose sum is σ = 61292267520. Its totient is φ = 5307120000.

The previous prime is 21056534501. The next prime is 21056534557. The reversal of 21056534550 is 5543565012.

21056534550 is a `hidden beast` number, since 2 + 1 + 0 + 56 + 53 + 4 + 550 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056534557) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1793700 + ... + 1805400.

It is an arithmetic number, because the mean of its divisors is an integer number (319230560).

Almost surely, 2^21056534550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21056534550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30646133760).

21056534550 is an abundant number, since it is smaller than the sum of its proper divisors (40235732970).

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

21056534550 is a wasteful number, since it uses less digits than its factorization.

21056534550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11796 (or 11785 counting only the distinct ones).

The product of its (nonzero) digits is 90000, while the sum is 36.

The spelling of 21056534550 in words is "twenty-one billion, fifty-six million, five hundred thirty-four thousand, five hundred fifty".