12215651221 has 4 divisors (see below), whose sum is σ = 12216046752. Its totient is φ = 12215255692.

The previous prime is 12215651213. The next prime is 12215651293.

12215651221 is nontrivially palindromic in base 10.

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 12215651221 - 2³ = 12215651213 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12215651221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12215651521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 147115 + ... + 214648.

It is an arithmetic number, because the mean of its divisors is an integer number (3054011688).

Almost surely, 2^12215651221 is an apocalyptic number.

It is an amenable number.

12215651221 is a deficient number, since it is larger than the sum of its proper divisors (395531).

12215651221 is an equidigital number, since it uses as much as digits as its factorization.

12215651221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395530.

The product of its digits is 2400, while the sum is 28.

The spelling of 12215651221 in words is "twelve billion, two hundred fifteen million, six hundred fifty-one thousand, two hundred twenty-one".