11921820 has 96 divisors (see below), whose sum is σ = 35707392. Its totient is φ = 2965248.

The previous prime is 11921773. The next prime is 11921827. The reversal of 11921820 is 2812911.

It is a super-3 number, since 3×11921820³ (a number of 22 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11921827) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 73059 + ... + 73221.

It is an arithmetic number, because the mean of its divisors is an integer number (371952).

Almost surely, 2^11921820 is an apocalyptic number.

11921820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 11921820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17853696).

11921820 is an abundant number, since it is smaller than the sum of its proper divisors (23785572).

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

11921820 is a wasteful number, since it uses less digits than its factorization.

11921820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251 (or 249 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 11921820 is about 3452.7988646893. The cubic root of 11921820 is about 228.4445773073. Note that the first 3 decimals are identical.

The spelling of 11921820 in words is "eleven million, nine hundred twenty-one thousand, eight hundred twenty".