21212233 has 16 divisors (see below), whose sum is σ = 25436160. Its totient is φ = 17295696.

The previous prime is 21212197. The next prime is 21212239. The reversal of 21212233 is 33221212.

It is a cyclic number.

It is not a de Polignac number, because 21212233 - 2⁹ = 21211721 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21212239) 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, 57616 + ... + 57982.

It is an arithmetic number, because the mean of its divisors is an integer number (1589760).

Almost surely, 2^21212233 is an apocalyptic number.

21212233 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21212233 is a deficient number, since it is larger than the sum of its proper divisors (4223927).

21212233 is a wasteful number, since it uses less digits than its factorization.

21212233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756.

The product of its digits is 144, while the sum is 16.

The square root of 21212233 is about 4605.6740006214. The cubic root of 21212233 is about 276.8187243353.

Adding to 21212233 its reverse (33221212), we get a palindrome (54433445).

The spelling of 21212233 in words is "twenty-one million, two hundred twelve thousand, two hundred thirty-three".