11812821 has 4 divisors (see below), whose sum is σ = 15750432. Its totient is φ = 7875212.

The previous prime is 11812819. The next prime is 11812849. The reversal of 11812821 is 12821811.

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: 12821811 = 3 ⋅4273937.

It is a cyclic number.

It is not a de Polignac number, because 11812821 - 2¹ = 11812819 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 11812791 and 11812800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11812811) 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, 1968801 + ... + 1968806.

It is an arithmetic number, because the mean of its divisors is an integer number (3937608).

Almost surely, 2^11812821 is an apocalyptic number.

It is an amenable number.

11812821 is a deficient number, since it is larger than the sum of its proper divisors (3937611).

11812821 is an equidigital number, since it uses as much as digits as its factorization.

11812821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3937610.

The product of its digits is 256, while the sum is 24.

The square root of 11812821 is about 3436.9784695281. The cubic root of 11812821 is about 227.7462358245.

The spelling of 11812821 in words is "eleven million, eight hundred twelve thousand, eight hundred twenty-one".