11821820 has 12 divisors (see below), whose sum is σ = 24825864. Its totient is φ = 4728720.

The previous prime is 11821787. The next prime is 11821841. The reversal of 11821820 is 2812811.

It is a happy number.

It is a super-2 number, since 2×11821820² = 279510856224800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 295526 + ... + 295565.

It is an arithmetic number, because the mean of its divisors is an integer number (2068822).

Almost surely, 2^11821820 is an apocalyptic number.

11821820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

11821820 is an abundant number, since it is smaller than the sum of its proper divisors (13004044).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11821820 is a wasteful number, since it uses less digits than its factorization.

11821820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 591100 (or 591098 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 11821820 is about 3438.2873643720. The cubic root of 11821820 is about 227.8040534608.

Subtracting from 11821820 its reverse (2812811), we obtain a palindrome (9009009).

The spelling of 11821820 in words is "eleven million, eight hundred twenty-one thousand, eight hundred twenty".