21506530611 has 4 divisors (see below), whose sum is σ = 28675374152. Its totient is φ = 14337687072.

The previous prime is 21506530583. The next prime is 21506530613. The reversal of 21506530611 is 11603560512.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21506530611 - 2⁹ = 21506530099 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21506530613) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3584421766 + ... + 3584421771.

It is an arithmetic number, because the mean of its divisors is an integer number (7168843538).

Almost surely, 2^21506530611 is an apocalyptic number.

21506530611 is a deficient number, since it is larger than the sum of its proper divisors (7168843541).

21506530611 is an equidigital number, since it uses as much as digits as its factorization.

21506530611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7168843540.

The product of its (nonzero) digits is 5400, while the sum is 30.

The spelling of 21506530611 in words is "twenty-one billion, five hundred six million, five hundred thirty thousand, six hundred eleven".