21675233 has 4 divisors (see below), whose sum is σ = 21972228. Its totient is φ = 21378240.

The previous prime is 21675211. The next prime is 21675239. The reversal of 21675233 is 33257612.

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 16581184 + 5094049 = 4072^2 + 2257^2 .

It is a cyclic number.

It is not a de Polignac number, because 21675233 - 2¹⁰ = 21674209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21675196 and 21675205.

It is not an unprimeable number, because it can be changed into a prime (21675239) 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 in 3 ways as a sum of consecutive naturals, for example, 148388 + ... + 148533.

It is an arithmetic number, because the mean of its divisors is an integer number (5493057).

Almost surely, 2^21675233 is an apocalyptic number.

It is an amenable number.

21675233 is a deficient number, since it is larger than the sum of its proper divisors (296995).

21675233 is an equidigital number, since it uses as much as digits as its factorization.

21675233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296994.

The product of its digits is 7560, while the sum is 29.

The square root of 21675233 is about 4655.6667621298. Note that the first 3 decimals coincide. The cubic root of 21675233 is about 278.8182892875.

The spelling of 21675233 in words is "twenty-one million, six hundred seventy-five thousand, two hundred thirty-three".