21308304 has 40 divisors (see below), whose sum is σ = 57442752. Its totient is φ = 6793600.

The previous prime is 21308303. The next prime is 21308311. The reversal of 21308304 is 40380312.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308303) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8547 + ... + 10754.

Almost surely, 2^21308304 is an apocalyptic number.

21308304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21308304 is an abundant number, since it is smaller than the sum of its proper divisors (36134448).

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

21308304 is a wasteful number, since it uses less digits than its factorization.

21308304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19335 (or 19329 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21308304 is about 4616.0918535055. The cubic root of 21308304 is about 277.2360024785.

Adding to 21308304 its reverse (40380312), we get a palindrome (61688616).

It can be divided in two parts, 21308 and 304, that added together give a palindrome (21612).

The spelling of 21308304 in words is "twenty-one million, three hundred eight thousand, three hundred four".