12215561 has 4 divisors (see below), whose sum is σ = 12262272. Its totient is φ = 12168852.

The previous prime is 12215557. The next prime is 12215573. The reversal of 12215561 is 16551221.

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 a cyclic number.

It is not a de Polignac number, because 12215561 - 2² = 12215557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12215531) 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, 22961 + ... + 23486.

It is an arithmetic number, because the mean of its divisors is an integer number (3065568).

Almost surely, 2^12215561 is an apocalyptic number.

It is an amenable number.

12215561 is a deficient number, since it is larger than the sum of its proper divisors (46711).

12215561 is an equidigital number, since it uses as much as digits as its factorization.

12215561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46710.

The product of its digits is 600, while the sum is 23.

The square root of 12215561 is about 3495.0766801316. The cubic root of 12215561 is about 230.3055862459.

Adding to 12215561 its reverse (16551221), we get a palindrome (28766782).

The spelling of 12215561 in words is "twelve million, two hundred fifteen thousand, five hundred sixty-one".