21026304 has 180 divisors, whose sum is σ = 68144076. Its totient is φ = 6469632.

The previous prime is 21026303. The next prime is 21026333. The reversal of 21026304 is 40362012.

It is a happy number.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21026303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1617402 + ... + 1617414.

Almost surely, 2^21026304 is an apocalyptic number.

21026304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21026304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34072038).

21026304 is an abundant number, since it is smaller than the sum of its proper divisors (47117772).

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

21026304 is an frugal number, since it uses more digits than its factorization.

21026304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59 (or 18 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21026304 is about 4585.4447984901. Note that the first 3 decimals coincide. The cubic root of 21026304 is about 276.0075612295.

Adding to 21026304 its reverse (40362012), we get a palindrome (61388316).

The spelling of 21026304 in words is "twenty-one million, twenty-six thousand, three hundred four".