12211821 has 6 divisors (see below), whose sum is σ = 17639310. Its totient is φ = 8141208.

The previous prime is 12211819. The next prime is 12211841. The reversal of 12211821 is 12811221.

It can be written as a sum of positive squares in only one way, i.e., 11594025 + 617796 = 3405^2 + 786^2 .

It is not a de Polignac number, because 12211821 - 2¹ = 12211819 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 12211794 and 12211803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12211841) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 678426 + ... + 678443.

It is an arithmetic number, because the mean of its divisors is an integer number (2939885).

Almost surely, 2^12211821 is an apocalyptic number.

It is an amenable number.

12211821 is a deficient number, since it is larger than the sum of its proper divisors (5427489).

12211821 is a wasteful number, since it uses less digits than its factorization.

12211821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1356875 (or 1356872 counting only the distinct ones).

The product of its digits is 64, while the sum is 18.

The square root of 12211821 is about 3494.5416008398. The cubic root of 12211821 is about 230.2820798671.

The spelling of 12211821 in words is "twelve million, two hundred eleven thousand, eight hundred twenty-one".