21805448 has 48 divisors (see below), whose sum is σ = 48497280. Its totient is φ = 9003456.

The previous prime is 21805417. The next prime is 21805451. The reversal of 21805448 is 84450812.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46865 + ... + 47327.

It is an arithmetic number, because the mean of its divisors is an integer number (1010360).

Almost surely, 2^21805448 is an apocalyptic number.

21805448 is a gapful number since it is divisible by the number (28) 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 21805448, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24248640).

21805448 is an abundant number, since it is smaller than the sum of its proper divisors (26691832).

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

21805448 is a wasteful number, since it uses less digits than its factorization.

21805448 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 534 (or 501 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 32.

The square root of 21805448 is about 4669.6303922259. The cubic root of 21805448 is about 279.3755129973.

The spelling of 21805448 in words is "twenty-one million, eight hundred five thousand, four hundred forty-eight".