11115561 has 4 divisors (see below), whose sum is σ = 14820752. Its totient is φ = 7410372.

The previous prime is 11115557. The next prime is 11115583. The reversal of 11115561 is 16551111.

It is a happy number.

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 not a de Polignac number, because 11115561 - 2² = 11115557 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (11115061) 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, 1852591 + ... + 1852596.

It is an arithmetic number, because the mean of its divisors is an integer number (3705188).

Almost surely, 2^11115561 is an apocalyptic number.

It is an amenable number.

11115561 is a deficient number, since it is larger than the sum of its proper divisors (3705191).

11115561 is an equidigital number, since it uses as much as digits as its factorization.

11115561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3705190.

The product of its digits is 150, while the sum is 21.

The square root of 11115561 is about 3334.0007498499. Note that the first 3 decimals coincide. The cubic root of 11115561 is about 223.1741017407.

Adding to 11115561 its reverse (16551111), we get a palindrome (27666672).

It can be divided in two parts, 111 and 15561, that multiplied together give a palindrome (1727271).

The spelling of 11115561 in words is "eleven million, one hundred fifteen thousand, five hundred sixty-one".