11821021 has 4 divisors (see below), whose sum is σ = 12443200. Its totient is φ = 11198844.

The previous prime is 11820971. The next prime is 11821027. The reversal of 11821021 is 12012811.

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: 12012811 = 167 ⋅71933.

It is a cyclic number.

It is not a de Polignac number, because 11821021 - 2¹¹ = 11818973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11820986 and 11821004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11821027) 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, 311061 + ... + 311098.

It is an arithmetic number, because the mean of its divisors is an integer number (3110800).

Almost surely, 2^11821021 is an apocalyptic number.

It is an amenable number.

11821021 is a deficient number, since it is larger than the sum of its proper divisors (622179).

11821021 is an equidigital number, since it uses as much as digits as its factorization.

11821021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622178.

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 11821021 is about 3438.1711708407. The cubic root of 11821021 is about 227.7989211563.

Adding to 11821021 its reverse (12012811), we get a palindrome (23833832).

The spelling of 11821021 in words is "eleven million, eight hundred twenty-one thousand, twenty-one".