16564253121 has 24 divisors (see below), whose sum is σ = 26119596776. Its totient is φ = 10053745920.

The previous prime is 16564253119. The next prime is 16564253149. The reversal of 16564253121 is 12135246561.

16564253121 is a `hidden beast` number, since 1 + 6 + 5 + 642 + 5 + 3 + 1 + 2 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 9828225 + 16554424896 = 3135^2 + 128664^2 .

It is not a de Polignac number, because 16564253121 - 2¹ = 16564253119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16564253221) 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 23 ways as a sum of consecutive naturals, for example, 961150 + ... + 978231.

Almost surely, 2^16564253121 is an apocalyptic number.

It is an amenable number.

16564253121 is a deficient number, since it is larger than the sum of its proper divisors (9555343655).

16564253121 is a wasteful number, since it uses less digits than its factorization.

16564253121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1939473 (or 1939470 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

Adding to 16564253121 its reverse (12135246561), we get a palindrome (28699499682).

The spelling of 16564253121 in words is "sixteen billion, five hundred sixty-four million, two hundred fifty-three thousand, one hundred twenty-one".