21443121 has 24 divisors (see below), whose sum is σ = 35740224. Its totient is φ = 12134880.

The previous prime is 21443119. The next prime is 21443129. The reversal of 21443121 is 12134412.

21443121 is a `hidden beast` number, since 214 + 431 + 21 = 666.

It is not a de Polignac number, because 21443121 - 2¹ = 21443119 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21443094 and 21443103.

It is not an unprimeable number, because it can be changed into a prime (21443129) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 5151 + ... + 8331.

It is an arithmetic number, because the mean of its divisors is an integer number (1489176).

Almost surely, 2^21443121 is an apocalyptic number.

21443121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21443121 is a deficient number, since it is larger than the sum of its proper divisors (14297103).

21443121 is a wasteful number, since it uses less digits than its factorization.

21443121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3301 (or 3298 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 21443121 is about 4630.6717655217. The cubic root of 21443121 is about 277.8194616497.

Adding to 21443121 its reverse (12134412), we get a palindrome (33577533).

The spelling of 21443121 in words is "twenty-one million, four hundred forty-three thousand, one hundred twenty-one".