13181561 has 4 divisors (see below), whose sum is σ = 13248000. Its totient is φ = 13115124.

The previous prime is 13181557. The next prime is 13181569. The reversal of 13181561 is 16518131.

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 13181561 - 2² = 13181557 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 13181561.

It is not an unprimeable number, because it can be changed into a prime (13181569) 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, 32921 + ... + 33318.

It is an arithmetic number, because the mean of its divisors is an integer number (3312000).

Almost surely, 2^13181561 is an apocalyptic number.

It is an amenable number.

13181561 is a deficient number, since it is larger than the sum of its proper divisors (66439).

13181561 is an equidigital number, since it uses as much as digits as its factorization.

13181561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66438.

The product of its digits is 720, while the sum is 26.

The square root of 13181561 is about 3630.6419542555. The cubic root of 13181561 is about 236.2230546987.

Adding to 13181561 its reverse (16518131), we get a palindrome (29699692).

The spelling of 13181561 in words is "thirteen million, one hundred eighty-one thousand, five hundred sixty-one".