12521819391 has 4 divisors (see below), whose sum is σ = 16695759192. Its totient is φ = 8347879592.

The previous prime is 12521819377. The next prime is 12521819417. The reversal of 12521819391 is 19391812521.

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

It is a cyclic number.

It is not a de Polignac number, because 12521819391 - 2³¹ = 10374335743 is a prime.

It is a super-2 number, since 2×12521819391² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12521819341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2086969896 + ... + 2086969901.

It is an arithmetic number, because the mean of its divisors is an integer number (4173939798).

Almost surely, 2^12521819391 is an apocalyptic number.

12521819391 is a deficient number, since it is larger than the sum of its proper divisors (4173939801).

12521819391 is an equidigital number, since it uses as much as digits as its factorization.

12521819391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4173939800.

The product of its digits is 38880, while the sum is 42.

The spelling of 12521819391 in words is "twelve billion, five hundred twenty-one million, eight hundred nineteen thousand, three hundred ninety-one".