12821421 has 4 divisors (see below), whose sum is σ = 17095232. Its totient is φ = 8547612.

The previous prime is 12821411. The next prime is 12821423. The reversal of 12821421 is 12412821.

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: 12412821 = 3 ⋅4137607.

It is not a de Polignac number, because 12821421 - 2⁶ = 12821357 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 (12821423) 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, 2136901 + ... + 2136906.

It is an arithmetic number, because the mean of its divisors is an integer number (4273808).

Almost surely, 2^12821421 is an apocalyptic number.

It is an amenable number.

12821421 is a deficient number, since it is larger than the sum of its proper divisors (4273811).

12821421 is an equidigital number, since it uses as much as digits as its factorization.

12821421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4273810.

The product of its digits is 256, while the sum is 21.

The square root of 12821421 is about 3580.7011883149. The cubic root of 12821421 is about 234.0518367153.

The spelling of 12821421 in words is "twelve million, eight hundred twenty-one thousand, four hundred twenty-one".