13212721 has 4 divisors (see below), whose sum is σ = 13241844. Its totient is φ = 13183600.

The previous prime is 13212713. The next prime is 13212743. The reversal of 13212721 is 12721231.

13212721 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 an emirpimes, since its reverse is a distinct semiprime: 12721231 = 23 ⋅553097.

It can be written as a sum of positive squares in 2 ways, for example, as 9678321 + 3534400 = 3111^2 + 1880^2 .

It is a cyclic number.

It is not a de Polignac number, because 13212721 - 2³ = 13212713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13212821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13870 + ... + 14791.

It is an arithmetic number, because the mean of its divisors is an integer number (3310461).

Almost surely, 2^13212721 is an apocalyptic number.

It is an amenable number.

13212721 is a deficient number, since it is larger than the sum of its proper divisors (29123).

13212721 is an equidigital number, since it uses as much as digits as its factorization.

13212721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29122.

The product of its digits is 168, while the sum is 19.

The square root of 13212721 is about 3634.9306733417. The cubic root of 13212721 is about 236.4090447590.

Adding to 13212721 its reverse (12721231), we get a palindrome (25933952).

The spelling of 13212721 in words is "thirteen million, two hundred twelve thousand, seven hundred twenty-one".