21489233 has 2 divisors, whose sum is σ = 21489234. Its totient is φ = 21489232.

The previous prime is 21489191. The next prime is 21489257. The reversal of 21489233 is 33298412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15618304 + 5870929 = 3952^2 + 2423^2 .

It is a cyclic number.

It is not a de Polignac number, because 21489233 - 2¹⁰ = 21488209 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21489233.

It is not a weakly prime, because it can be changed into another prime (21489833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10744616 + 10744617.

It is an arithmetic number, because the mean of its divisors is an integer number (10744617).

Almost surely, 2^21489233 is an apocalyptic number.

It is an amenable number.

21489233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21489233 is an equidigital number, since it uses as much as digits as its factorization.

21489233 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 32.

The square root of 21489233 is about 4635.6480668834. The cubic root of 21489233 is about 278.0184631390.

The spelling of 21489233 in words is "twenty-one million, four hundred eighty-nine thousand, two hundred thirty-three".