12811561 has 4 divisors (see below), whose sum is σ = 14641792. Its totient is φ = 10981332.

The previous prime is 12811559. The next prime is 12811571. The reversal of 12811561 is 16511821.

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 12811561 - 2¹ = 12811559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12811511) 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, 915105 + ... + 915118.

It is an arithmetic number, because the mean of its divisors is an integer number (3660448).

Almost surely, 2^12811561 is an apocalyptic number.

It is an amenable number.

12811561 is a deficient number, since it is larger than the sum of its proper divisors (1830231).

12811561 is an equidigital number, since it uses as much as digits as its factorization.

12811561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1830230.

The product of its digits is 480, while the sum is 25.

The square root of 12811561 is about 3579.3240982063. The cubic root of 12811561 is about 233.9918240502.

The spelling of 12811561 in words is "twelve million, eight hundred eleven thousand, five hundred sixty-one".