21042433 has 4 divisors (see below), whose sum is σ = 21129988. Its totient is φ = 20954880.

The previous prime is 21042419. The next prime is 21042449. The reversal of 21042433 is 33424012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7551504 + 13490929 = 2748^2 + 3673^2 .

It is a cyclic number.

It is not a de Polignac number, because 21042433 - 2²¹ = 18945281 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21042433.

It is not an unprimeable number, because it can be changed into a prime (21042473) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 43416 + ... + 43897.

It is an arithmetic number, because the mean of its divisors is an integer number (5282497).

Almost surely, 2^21042433 is an apocalyptic number.

It is an amenable number.

21042433 is a deficient number, since it is larger than the sum of its proper divisors (87555).

21042433 is an equidigital number, since it uses as much as digits as its factorization.

21042433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87554.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21042433 is about 4587.2031784084. The cubic root of 21042433 is about 276.0781171096.

Adding to 21042433 its reverse (33424012), we get a palindrome (54466445).

The spelling of 21042433 in words is "twenty-one million, forty-two thousand, four hundred thirty-three".