13666221 has 12 divisors (see below), whose sum is σ = 20421180. Its totient is φ = 8796480.

The previous prime is 13666193. The next prime is 13666223. The reversal of 13666221 is 12266631.

13666221 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 3515625 + 10150596 = 1875^2 + 3186^2 .

It is not a de Polignac number, because 13666221 - 2⁵ = 13666189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13666223) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25920 + ... + 26441.

It is an arithmetic number, because the mean of its divisors is an integer number (1701765).

Almost surely, 2^13666221 is an apocalyptic number.

It is an amenable number.

13666221 is a deficient number, since it is larger than the sum of its proper divisors (6754959).

13666221 is a wasteful number, since it uses less digits than its factorization.

13666221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52396 (or 52393 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 13666221 is about 3696.7852250300. The cubic root of 13666221 is about 239.0834311290.

The spelling of 13666221 in words is "thirteen million, six hundred sixty-six thousand, two hundred twenty-one".