21043121 has 16 divisors (see below), whose sum is σ = 23803200. Its totient is φ = 18434880.

The previous prime is 21043111. The next prime is 21043123. The reversal of 21043121 is 12134012.

It is not a de Polignac number, because 21043121 - 2¹⁰ = 21042097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21043096 and 21043105.

It is not an unprimeable number, because it can be changed into a prime (21043123) 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 15 ways as a sum of consecutive naturals, for example, 60470 + ... + 60816.

It is an arithmetic number, because the mean of its divisors is an integer number (1487700).

Almost surely, 2^21043121 is an apocalyptic number.

It is an amenable number.

21043121 is a deficient number, since it is larger than the sum of its proper divisors (2760079).

21043121 is a wasteful number, since it uses less digits than its factorization.

21043121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21043121 is about 4587.2781690235. The cubic root of 21043121 is about 276.0811259454.

Adding to 21043121 its reverse (12134012), we get a palindrome (33177133).

It can be divided in two parts, 2104 and 3121, that added together give a palindrome (5225).

The spelling of 21043121 in words is "twenty-one million, forty-three thousand, one hundred twenty-one".