1213821 has 12 divisors (see below), whose sum is σ = 2003872. Its totient is φ = 693576.

The previous prime is 1213801. The next prime is 1213829. The reversal of 1213821 is 1283121.

It is not a de Polignac number, because 1213821 - 2⁶ = 1213757 is a prime.

It is a super-2 number, since 2×1213821² = 2946722840082, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1213794 and 1213803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9571 + ... + 9696.

2^1213821 is an apocalyptic number.

It is an amenable number.

1213821 is a deficient number, since it is larger than the sum of its proper divisors (790051).

1213821 is a wasteful number, since it uses less digits than its factorization.

1213821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19280 (or 19277 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 1213821 is about 1101.7354491891. The cubic root of 1213821 is about 106.6722729258.

Adding to 1213821 its reverse (1283121), we get a palindrome (2496942).

The spelling of 1213821 in words is "one million, two hundred thirteen thousand, eight hundred twenty-one".