11820021 has 16 divisors (see below), whose sum is σ = 16396800. Its totient is φ = 7565760.

The previous prime is 11820019. The next prime is 11820037. The reversal of 11820021 is 12002811.

It is not a de Polignac number, because 11820021 - 2¹ = 11820019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11820041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13431 + ... + 14283.

It is an arithmetic number, because the mean of its divisors is an integer number (1024800).

Almost surely, 2^11820021 is an apocalyptic number.

It is an amenable number.

11820021 is a deficient number, since it is larger than the sum of its proper divisors (4576779).

11820021 is a wasteful number, since it uses less digits than its factorization.

11820021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1036.

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 11820021 is about 3438.0257416139. The cubic root of 11820021 is about 227.7924974205.

Adding to 11820021 its reverse (12002811), we get a palindrome (23822832).

The spelling of 11820021 in words is "eleven million, eight hundred twenty thousand, twenty-one".