12816999521 has 4 divisors (see below), whose sum is σ = 12914839344. Its totient is φ = 12719159700.

The previous prime is 12816999509. The next prime is 12816999539. The reversal of 12816999521 is 12599961821.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12816999521 - 2¹⁰ = 12816998497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12816999571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48919715 + ... + 48919976.

It is an arithmetic number, because the mean of its divisors is an integer number (3228709836).

Almost surely, 2^12816999521 is an apocalyptic number.

It is an amenable number.

12816999521 is a deficient number, since it is larger than the sum of its proper divisors (97839823).

12816999521 is an equidigital number, since it uses as much as digits as its factorization.

12816999521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97839822.

The product of its digits is 699840, while the sum is 53.

The spelling of 12816999521 in words is "twelve billion, eight hundred sixteen million, nine hundred ninety-nine thousand, five hundred twenty-one".