21212304 has 20 divisors (see below), whose sum is σ = 54798576. Its totient is φ = 7070752.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212304 is 40321212.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220914 + ... + 221009.

Almost surely, 2^21212304 is an apocalyptic number.

21212304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21212304 is an abundant number, since it is smaller than the sum of its proper divisors (33586272).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21212304 is a wasteful number, since it uses less digits than its factorization.

21212304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441934 (or 441928 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21212304 is about 4605.6817084988. The cubic root of 21212304 is about 276.8190331840.

Adding to 21212304 its reverse (40321212), we get a palindrome (61533516).

The spelling of 21212304 in words is "twenty-one million, two hundred twelve thousand, three hundred four".