11215561 has 12 divisors (see below), whose sum is σ = 13352592. Its totient is φ = 9388008.

The previous prime is 11215549. The next prime is 11215579. The reversal of 11215561 is 16551211.

It is a happy number.

11215561 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11215561 - 2⁹ = 11215049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11215511) 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 11 ways as a sum of consecutive naturals, for example, 555 + ... + 4768.

It is an arithmetic number, because the mean of its divisors is an integer number (1112716).

Almost surely, 2^11215561 is an apocalyptic number.

It is an amenable number.

11215561 is a deficient number, since it is larger than the sum of its proper divisors (2137031).

11215561 is an equidigital number, since it uses as much as digits as its factorization.

11215561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5380 (or 5373 counting only the distinct ones).

The product of its digits is 300, while the sum is 22.

The square root of 11215561 is about 3348.9641682168. The cubic root of 11215561 is about 223.8413590282.

Adding to 11215561 its reverse (16551211), we get a palindrome (27766772).

The spelling of 11215561 in words is "eleven million, two hundred fifteen thousand, five hundred sixty-one".