21212446 has 4 divisors (see below), whose sum is σ = 31818672. Its totient is φ = 10606222.

The previous prime is 21212431. The next prime is 21212449. The reversal of 21212446 is 64421212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212449) 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, 5303110 + ... + 5303113.

It is an arithmetic number, because the mean of its divisors is an integer number (7954668).

Almost surely, 2^21212446 is an apocalyptic number.

21212446 is a deficient number, since it is larger than the sum of its proper divisors (10606226).

21212446 is a wasteful number, since it uses less digits than its factorization.

21212446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10606225.

The product of its digits is 768, while the sum is 22.

The square root of 21212446 is about 4605.6971242147. The cubic root of 21212446 is about 276.8196508792.

Adding to 21212446 its reverse (64421212), we get a palindrome (85633658).

The spelling of 21212446 in words is "twenty-one million, two hundred twelve thousand, four hundred forty-six".