12266721 has 20 divisors (see below), whose sum is σ = 18824212. Its totient is φ = 7954848.

The previous prime is 12266719. The next prime is 12266729. The reversal of 12266721 is 12766221.

It can be written as a sum of positive squares in 2 ways, for example, as 8346321 + 3920400 = 2889^2 + 1980^2 .

It is not a de Polignac number, because 12266721 - 2¹ = 12266719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12266729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 951 + ... + 5043.

Almost surely, 2^12266721 is an apocalyptic number.

It is an amenable number.

12266721 is a deficient number, since it is larger than the sum of its proper divisors (6557491).

12266721 is an equidigital number, since it uses as much as digits as its factorization.

12266721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4142 (or 4133 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 12266721 is about 3502.3878997050. The cubic root of 12266721 is about 230.6266527742.

Subtracting 12266721 from its reverse (12766221), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 12266721 in words is "twelve million, two hundred sixty-six thousand, seven hundred twenty-one".