21500055126 has 192 divisors, whose sum is σ = 54690451200. Its totient is φ = 6250970880.

The previous prime is 21500055113. The next prime is 21500055151. The reversal of 21500055126 is 62155000512.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21500055126.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 16576110 + ... + 16577406.

It is an arithmetic number, because the mean of its divisors is an integer number (284846100).

Almost surely, 2^21500055126 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21500055126, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27345225600).

21500055126 is an abundant number, since it is smaller than the sum of its proper divisors (33190396074).

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

21500055126 is a wasteful number, since it uses less digits than its factorization.

21500055126 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1432 (or 1415 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

Adding to 21500055126 its reverse (62155000512), we get a palindrome (83655055638).

The spelling of 21500055126 in words is "twenty-one billion, five hundred million, fifty-five thousand, one hundred twenty-six".