13031561 has 2 divisors, whose sum is σ = 13031562. Its totient is φ = 13031560.

The previous prime is 13031539. The next prime is 13031617. The reversal of 13031561 is 16513031.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9859600 + 3171961 = 3140^2 + 1781^2 .

It is an emirp because it is prime and its reverse (16513031) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13031561 - 2¹⁸ = 12769417 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (13031521) 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 as a sum of consecutive naturals, namely, 6515780 + 6515781.

It is an arithmetic number, because the mean of its divisors is an integer number (6515781).

Almost surely, 2^13031561 is an apocalyptic number.

It is an amenable number.

13031561 is a deficient number, since it is larger than the sum of its proper divisors (1).

13031561 is an equidigital number, since it uses as much as digits as its factorization.

13031561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 270, while the sum is 20.

The square root of 13031561 is about 3609.9253454885. The cubic root of 13031561 is about 235.3235982583.

Adding to 13031561 its reverse (16513031), we get a palindrome (29544592).

The spelling of 13031561 in words is "thirteen million, thirty-one thousand, five hundred sixty-one".