13131221 has 4 divisors (see below), whose sum is σ = 13219500. Its totient is φ = 13042944.

The previous prime is 13131203. The next prime is 13131233. The reversal of 13131221 is 12213131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12213131 = 7 ⋅1744733.

It can be written as a sum of positive squares in 2 ways, for example, as 2208196 + 10923025 = 1486^2 + 3305^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13131221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13131196 and 13131205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13131241) 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 3 ways as a sum of consecutive naturals, for example, 43916 + ... + 44213.

It is an arithmetic number, because the mean of its divisors is an integer number (3304875).

Almost surely, 2^13131221 is an apocalyptic number.

It is an amenable number.

13131221 is a deficient number, since it is larger than the sum of its proper divisors (88279).

13131221 is an equidigital number, since it uses as much as digits as its factorization.

13131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88278.

The product of its digits is 36, while the sum is 14.

The square root of 13131221 is about 3623.7026644028. The cubic root of 13131221 is about 235.9219614140.

Adding to 13131221 its reverse (12213131), we get a palindrome (25344352).

The spelling of 13131221 in words is "thirteen million, one hundred thirty-one thousand, two hundred twenty-one".