21545044500 has 192 divisors, whose sum is σ = 73641125376. Its totient is φ = 4791398400.

The previous prime is 21545044489. The next prime is 21545044561. The reversal of 21545044500 is 544054512.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 63 ways as a sum of consecutive naturals, for example, 360772 + ... + 416228.

It is an arithmetic number, because the mean of its divisors is an integer number (383547528).

Almost surely, 2^21545044500 is an apocalyptic number.

21545044500 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 21545044500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36820562688).

21545044500 is an abundant number, since it is smaller than the sum of its proper divisors (52096080876).

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

21545044500 is a wasteful number, since it uses less digits than its factorization.

21545044500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55523 (or 55511 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 30.

The spelling of 21545044500 in words is "twenty-one billion, five hundred forty-five million, forty-four thousand, five hundred".