21405500512 has 48 divisors (see below), whose sum is σ = 46049375232. Its totient is φ = 9713646720.

The previous prime is 21405500509. The next prime is 21405500563. The reversal of 21405500512 is 21500550412.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 163573 + ... + 263755.

It is an arithmetic number, because the mean of its divisors is an integer number (959361984).

Almost surely, 2^21405500512 is an apocalyptic number.

21405500512 is a gapful number since it is divisible by the number (22) 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 21405500512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23024687616).

21405500512 is an abundant number, since it is smaller than the sum of its proper divisors (24643874720).

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

21405500512 is a wasteful number, since it uses less digits than its factorization.

21405500512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100811 (or 100803 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

The spelling of 21405500512 in words is "twenty-one billion, four hundred five million, five hundred thousand, five hundred twelve".