11155561 has 2 divisors, whose sum is σ = 11155562. Its totient is φ = 11155560.

The previous prime is 11155549. The next prime is 11155579. The reversal of 11155561 is 16555111.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10523536 + 632025 = 3244^2 + 795^2 .

It is an emirp because it is prime and its reverse (16555111) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 11155561 - 2⁹ = 11155049 is a prime.

It is a nialpdrome in base 15.

It is not a weakly prime, because it can be changed into another prime (11155541) 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, 5577780 + 5577781.

It is an arithmetic number, because the mean of its divisors is an integer number (5577781).

Almost surely, 2^11155561 is an apocalyptic number.

It is an amenable number.

11155561 is a deficient number, since it is larger than the sum of its proper divisors (1).

11155561 is an equidigital number, since it uses as much as digits as its factorization.

11155561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 750, while the sum is 25.

The square root of 11155561 is about 3339.9941616715. The cubic root of 11155561 is about 223.4414829779.

It can be divided in two parts, 11 and 155561, that multiplied together give a palindrome (1711171).

The spelling of 11155561 in words is "eleven million, one hundred fifty-five thousand, five hundred sixty-one".