16265531521 has 4 divisors (see below), whose sum is σ = 16662251844. Its totient is φ = 15868811200.

The previous prime is 16265531519. The next prime is 16265531539. The reversal of 16265531521 is 12513556261.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1874890000 + 14390641521 = 43300^2 + 119961^2 .

It is a cyclic number.

It is not a de Polignac number, because 16265531521 - 2¹ = 16265531519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16265531501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198360100 + ... + 198360181.

It is an arithmetic number, because the mean of its divisors is an integer number (4165562961).

Almost surely, 2^16265531521 is an apocalyptic number.

It is an amenable number.

16265531521 is a deficient number, since it is larger than the sum of its proper divisors (396720323).

16265531521 is an equidigital number, since it uses as much as digits as its factorization.

16265531521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396720322.

The product of its digits is 54000, while the sum is 37.

The spelling of 16265531521 in words is "sixteen billion, two hundred sixty-five million, five hundred thirty-one thousand, five hundred twenty-one".