12817561 has 4 divisors (see below), whose sum is σ = 12844800. Its totient is φ = 12790324.

The previous prime is 12817549. The next prime is 12817579. The reversal of 12817561 is 16571821.

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 12817561 - 2⁵ = 12817529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12817531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12901 + ... + 13858.

It is an arithmetic number, because the mean of its divisors is an integer number (3211200).

Almost surely, 2^12817561 is an apocalyptic number.

It is an amenable number.

12817561 is a deficient number, since it is larger than the sum of its proper divisors (27239).

12817561 is an equidigital number, since it uses as much as digits as its factorization.

12817561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27238.

The product of its digits is 3360, while the sum is 31.

The square root of 12817561 is about 3580.1621471660. The cubic root of 12817561 is about 234.0283465794.

It can be divided in two parts, 128 and 17561, that added together give a square (17689 = 133²).

The spelling of 12817561 in words is "twelve million, eight hundred seventeen thousand, five hundred sixty-one".