21120843 has 4 divisors (see below), whose sum is σ = 28161128. Its totient is φ = 14080560.

The previous prime is 21120833. The next prime is 21120893. The reversal of 21120843 is 34802112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21120843 - 2⁵ = 21120811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21120833) 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 3 ways as a sum of consecutive naturals, for example, 3520138 + ... + 3520143.

It is an arithmetic number, because the mean of its divisors is an integer number (7040282).

Almost surely, 2^21120843 is an apocalyptic number.

21120843 is a deficient number, since it is larger than the sum of its proper divisors (7040285).

21120843 is an equidigital number, since it uses as much as digits as its factorization.

21120843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7040284.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21120843 is about 4595.7418334802. The cubic root of 21120843 is about 276.4206068578.

Adding to 21120843 its reverse (34802112), we get a palindrome (55922955).

The spelling of 21120843 in words is "twenty-one million, one hundred twenty thousand, eight hundred forty-three".