11810821 has 4 divisors (see below), whose sum is σ = 12884544. Its totient is φ = 10737100.

The previous prime is 11810803. The next prime is 11810833. The reversal of 11810821 is 12801811.

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 11810821 - 2⁵ = 11810789 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11810792 and 11810801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11810021) 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, 536845 + ... + 536866.

It is an arithmetic number, because the mean of its divisors is an integer number (3221136).

Almost surely, 2^11810821 is an apocalyptic number.

11810821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11810821 is a deficient number, since it is larger than the sum of its proper divisors (1073723).

11810821 is a wasteful number, since it uses less digits than its factorization.

11810821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1073722.

The product of its (nonzero) digits is 128, while the sum is 22.

The square root of 11810821 is about 3436.6875039782. The cubic root of 11810821 is about 227.7333820453.

The spelling of 11810821 in words is "eleven million, eight hundred ten thousand, eight hundred twenty-one".