12840521 has 4 divisors (see below), whose sum is σ = 12864132. Its totient is φ = 12816912.

The previous prime is 12840493. The next prime is 12840539. The reversal of 12840521 is 12504821.

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 5112121 + 7728400 = 2261^2 + 2780^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12840521 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12840551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10970 + ... + 12083.

It is an arithmetic number, because the mean of its divisors is an integer number (3216033).

Almost surely, 2^12840521 is an apocalyptic number.

It is an amenable number.

12840521 is a deficient number, since it is larger than the sum of its proper divisors (23611).

12840521 is an equidigital number, since it uses as much as digits as its factorization.

12840521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23610.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 12840521 is about 3583.3672711571. The cubic root of 12840521 is about 234.1680009605.

The spelling of 12840521 in words is "twelve million, eight hundred forty thousand, five hundred twenty-one".