13531561 has 4 divisors (see below), whose sum is σ = 13572052. Its totient is φ = 13491072.

The previous prime is 13531559. The next prime is 13531571. The reversal of 13531561 is 16513531.

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 5494336 + 8037225 = 2344^2 + 2835^2 .

It is a cyclic number.

It is not a de Polignac number, because 13531561 - 2¹ = 13531559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13531501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19740 + ... + 20413.

It is an arithmetic number, because the mean of its divisors is an integer number (3393013).

Almost surely, 2^13531561 is an apocalyptic number.

It is an amenable number.

13531561 is a deficient number, since it is larger than the sum of its proper divisors (40491).

13531561 is an equidigital number, since it uses as much as digits as its factorization.

13531561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40490.

The product of its digits is 1350, while the sum is 25.

The square root of 13531561 is about 3678.5270149885. The cubic root of 13531561 is about 238.2955688068.

The spelling of 13531561 in words is "thirteen million, five hundred thirty-one thousand, five hundred sixty-one".