21212204 has 18 divisors (see below), whose sum is σ = 40197780. Its totient is φ = 9789936.

The previous prime is 21212197. The next prime is 21212239. The reversal of 21212204 is 40221212.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 15014 + ... + 16365.

It is an arithmetic number, because the mean of its divisors is an integer number (2233210).

Almost surely, 2^21212204 is an apocalyptic number.

It is an amenable number.

21212204 is a deficient number, since it is larger than the sum of its proper divisors (18985576).

21212204 is a wasteful number, since it uses less digits than its factorization.

21212204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31409 (or 31394 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21212204 is about 4605.6708523298. The cubic root of 21212204 is about 276.8185981857.

Adding to 21212204 its reverse (40221212), we get a palindrome (61433416).

The spelling of 21212204 in words is "twenty-one million, two hundred twelve thousand, two hundred four".