21112665521 has 8 divisors (see below), whose sum is σ = 21918421800. Its totient is φ = 20312091520.

The previous prime is 21112665491. The next prime is 21112665523. The reversal of 21112665521 is 12556621112.

It can be written as a sum of positive squares in 4 ways, for example, as 510082225 + 20602583296 = 22585^2 + 143536^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21112665521 - 2¹⁴ = 21112649137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112665523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1287266 + ... + 1303563.

It is an arithmetic number, because the mean of its divisors is an integer number (2739802725).

Almost surely, 2^21112665521 is an apocalyptic number.

It is an amenable number.

21112665521 is a deficient number, since it is larger than the sum of its proper divisors (805756279).

21112665521 is a wasteful number, since it uses less digits than its factorization.

21112665521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2591139.

The product of its digits is 7200, while the sum is 32.

The spelling of 21112665521 in words is "twenty-one billion, one hundred twelve million, six hundred sixty-five thousand, five hundred twenty-one".