13557221 has 4 divisors (see below), whose sum is σ = 13684032. Its totient is φ = 13430412.

The previous prime is 13557217. The next prime is 13557251. The reversal of 13557221 is 12275531.

13557221 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12275531 = 647 ⋅18973.

It is a cyclic number.

It is not a de Polignac number, because 13557221 - 2² = 13557217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13557251) 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, 63245 + ... + 63458.

It is an arithmetic number, because the mean of its divisors is an integer number (3421008).

Almost surely, 2^13557221 is an apocalyptic number.

It is an amenable number.

13557221 is a deficient number, since it is larger than the sum of its proper divisors (126811).

13557221 is a wasteful number, since it uses less digits than its factorization.

13557221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126810.

The product of its digits is 2100, while the sum is 26.

The square root of 13557221 is about 3682.0131721655. The cubic root of 13557221 is about 238.4461009164.

The spelling of 13557221 in words is "thirteen million, five hundred fifty-seven thousand, two hundred twenty-one".