12213921 has 4 divisors (see below), whose sum is σ = 16285232. Its totient is φ = 8142612.

The previous prime is 12213913. The next prime is 12213923. The reversal of 12213921 is 12931221.

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.

It is not a de Polignac number, because 12213921 - 2³ = 12213913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12213923) 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, 2035651 + ... + 2035656.

It is an arithmetic number, because the mean of its divisors is an integer number (4071308).

Almost surely, 2^12213921 is an apocalyptic number.

It is an amenable number.

12213921 is a deficient number, since it is larger than the sum of its proper divisors (4071311).

12213921 is an equidigital number, since it uses as much as digits as its factorization.

12213921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4071310.

The product of its digits is 216, while the sum is 21.

The square root of 12213921 is about 3494.8420565170. The cubic root of 12213921 is about 230.2952792267.

The spelling of 12213921 in words is "twelve million, two hundred thirteen thousand, nine hundred twenty-one".