12219821 has 4 divisors (see below), whose sum is σ = 12938652. Its totient is φ = 11500992.

The previous prime is 12219803. The next prime is 12219827. The reversal of 12219821 is 12891221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12891221 = 7 ⋅1841603.

It can be written as a sum of positive squares in 2 ways, for example, as 3279721 + 8940100 = 1811^2 + 2990^2 .

It is a cyclic number.

It is not a de Polignac number, because 12219821 - 2¹⁴ = 12203437 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 (12219827) 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, 359390 + ... + 359423.

It is an arithmetic number, because the mean of its divisors is an integer number (3234663).

Almost surely, 2^12219821 is an apocalyptic number.

It is an amenable number.

12219821 is a deficient number, since it is larger than the sum of its proper divisors (718831).

12219821 is an equidigital number, since it uses as much as digits as its factorization.

12219821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 718830.

The product of its digits is 576, while the sum is 26.

The square root of 12219821 is about 3495.6860556978. The cubic root of 12219821 is about 230.3323550471.

The spelling of 12219821 in words is "twelve million, two hundred nineteen thousand, eight hundred twenty-one".