21841920 has 192 divisors, whose sum is σ = 78624000. Its totient is φ = 5750784.

The previous prime is 21841913. The next prime is 21842021. The reversal of 21841920 is 2914812.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 276441 + ... + 276519.

It is an arithmetic number, because the mean of its divisors is an integer number (409500).

Almost surely, 2^21841920 is an apocalyptic number.

21841920 is a gapful number since it is divisible by the number (20) 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 21841920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39312000).

21841920 is an abundant number, since it is smaller than the sum of its proper divisors (56782080).

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

21841920 is an equidigital number, since it uses as much as digits as its factorization.

21841920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21841920 is about 4673.5339947410. The cubic root of 21841920 is about 279.5311882828.

The spelling of 21841920 in words is "twenty-one million, eight hundred forty-one thousand, nine hundred twenty".