13111221 has 4 divisors (see below), whose sum is σ = 17481632. Its totient is φ = 8740812.

The previous prime is 13111211. The next prime is 13111229. The reversal of 13111221 is 12211131.

13111221 is digitally balanced in base 2, 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: 12211131 = 3 ⋅4070377.

It is not a de Polignac number, because 13111221 - 2⁷ = 13111093 is a prime.

It is a super-2 number, since 2×13111221² = 343808232221682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13111197 and 13111206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13111229) 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, 2185201 + ... + 2185206.

It is an arithmetic number, because the mean of its divisors is an integer number (4370408).

Almost surely, 2^13111221 is an apocalyptic number.

It is an amenable number.

13111221 is a deficient number, since it is larger than the sum of its proper divisors (4370411).

13111221 is an equidigital number, since it uses as much as digits as its factorization.

13111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4370410.

The product of its digits is 12, while the sum is 12.

The square root of 13111221 is about 3620.9420045066. The cubic root of 13111221 is about 235.8021239470.

Adding to 13111221 its reverse (12211131), we get a palindrome (25322352).

The spelling of 13111221 in words is "thirteen million, one hundred eleven thousand, two hundred twenty-one".