21233217 has 4 divisors (see below), whose sum is σ = 28310960. Its totient is φ = 14155476.

The previous prime is 21233213. The next prime is 21233239. The reversal of 21233217 is 71233212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21233217 - 2² = 21233213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21233193 and 21233202.

It is not an unprimeable number, because it can be changed into a prime (21233213) 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, 3538867 + ... + 3538872.

It is an arithmetic number, because the mean of its divisors is an integer number (7077740).

It is a self-describing number.

Almost surely, 2^21233217 is an apocalyptic number.

It is an amenable number.

21233217 is a deficient number, since it is larger than the sum of its proper divisors (7077743).

21233217 is an equidigital number, since it uses as much as digits as its factorization.

21233217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7077742.

The product of its digits is 504, while the sum is 21.

The square root of 21233217 is about 4607.9514971406. The cubic root of 21233217 is about 276.9099743504.

Adding to 21233217 its reverse (71233212), we get a palindrome (92466429).

The spelling of 21233217 in words is "twenty-one million, two hundred thirty-three thousand, two hundred seventeen".