13111561 has 2 divisors, whose sum is σ = 13111562. Its totient is φ = 13111560.

The previous prime is 13111519. The next prime is 13111583. The reversal of 13111561 is 16511131.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13097161 + 14400 = 3619^2 + 120^2 .

It is a cyclic number.

It is not a de Polignac number, because 13111561 - 2⁷ = 13111433 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (13111661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6555780 + 6555781.

It is an arithmetic number, because the mean of its divisors is an integer number (6555781).

Almost surely, 2^13111561 is an apocalyptic number.

13111561 is the 1936-th centered heptagonal number.

It is an amenable number.

13111561 is a deficient number, since it is larger than the sum of its proper divisors (1).

13111561 is an equidigital number, since it uses as much as digits as its factorization.

13111561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90, while the sum is 19.

The square root of 13111561 is about 3620.9889533110. The cubic root of 13111561 is about 235.8041622018.

Adding to 13111561 its reverse (16511131), we get a palindrome (29622692).

The spelling of 13111561 in words is "thirteen million, one hundred eleven thousand, five hundred sixty-one".