12218421 has 4 divisors (see below), whose sum is σ = 16291232. Its totient is φ = 8145612.

The previous prime is 12218417. The next prime is 12218443. The reversal of 12218421 is 12481221.

12218421 is digitally balanced in base 2 and base 4, because in such bases 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: 12481221 = 3 ⋅4160407.

It is not a de Polignac number, because 12218421 - 2² = 12218417 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 (12218491) 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, 2036401 + ... + 2036406.

It is an arithmetic number, because the mean of its divisors is an integer number (4072808).

Almost surely, 2^12218421 is an apocalyptic number.

It is an amenable number.

12218421 is a deficient number, since it is larger than the sum of its proper divisors (4072811).

12218421 is an equidigital number, since it uses as much as digits as its factorization.

12218421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4072810.

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

The square root of 12218421 is about 3495.4858031467. The cubic root of 12218421 is about 230.3235584749.

Adding to 12218421 its reverse (12481221), we get a palindrome (24699642).

The spelling of 12218421 in words is "twelve million, two hundred eighteen thousand, four hundred twenty-one".