21212241 has 4 divisors (see below), whose sum is σ = 28282992. Its totient is φ = 14141492.

The previous prime is 21212239. The next prime is 21212263. The reversal of 21212241 is 14221212.

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 a cyclic number.

It is not a de Polignac number, because 21212241 - 2¹ = 21212239 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21212241.

It is not an unprimeable number, because it can be changed into a prime (21212281) 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 3 ways as a sum of consecutive naturals, for example, 3535371 + ... + 3535376.

It is an arithmetic number, because the mean of its divisors is an integer number (7070748).

Almost surely, 2^21212241 is an apocalyptic number.

It is an amenable number.

21212241 is a deficient number, since it is larger than the sum of its proper divisors (7070751).

21212241 is an equidigital number, since it uses as much as digits as its factorization.

21212241 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7070750.

The product of its digits is 64, while the sum is 15.

The square root of 21212241 is about 4605.6748691153. The cubic root of 21212241 is about 276.8187591352.

Adding to 21212241 its reverse (14221212), we get a palindrome (35433453).

The spelling of 21212241 in words is "twenty-one million, two hundred twelve thousand, two hundred forty-one".