21105503571 has 8 divisors (see below), whose sum is σ = 28313314240. Its totient is φ = 13984014312.

The previous prime is 21105503537. The next prime is 21105503603. The reversal of 21105503571 is 17530550112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21105503571 - 2⁷ = 21105503443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21105503171) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21579781 + ... + 21580758.

It is an arithmetic number, because the mean of its divisors is an integer number (3539164280).

Almost surely, 2^21105503571 is an apocalyptic number.

21105503571 is a deficient number, since it is larger than the sum of its proper divisors (7207810669).

21105503571 is a wasteful number, since it uses less digits than its factorization.

21105503571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43160705.

The product of its (nonzero) digits is 5250, while the sum is 30.

The spelling of 21105503571 in words is "twenty-one billion, one hundred five million, five hundred three thousand, five hundred seventy-one".