21105503580 has 192 divisors, whose sum is σ = 69310015488. Its totient is φ = 4697948160.

The previous prime is 21105503537. The next prime is 21105503603. The reversal of 21105503580 is 8530550112.

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 polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 18304284 + ... + 18305436.

It is an arithmetic number, because the mean of its divisors is an integer number (360989664).

Almost surely, 2^21105503580 is an apocalyptic number.

21105503580 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 21105503580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34655007744).

21105503580 is an abundant number, since it is smaller than the sum of its proper divisors (48204511908).

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

21105503580 is a wasteful number, since it uses less digits than its factorization.

21105503580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2276 (or 2274 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 30.

The spelling of 21105503580 in words is "twenty-one billion, one hundred five million, five hundred three thousand, five hundred eighty".