21272304 has 80 divisors (see below), whose sum is σ = 58924800. Its totient is φ = 6589440.

The previous prime is 21272297. The next prime is 21272311. The reversal of 21272304 is 40327212.

It is an interprime number because it is at equal distance from previous prime (21272297) and next prime (21272311).

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 106797 + ... + 106995.

It is an arithmetic number, because the mean of its divisors is an integer number (736560).

Almost surely, 2^21272304 is an apocalyptic number.

21272304 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 21272304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29462400).

21272304 is an abundant number, since it is smaller than the sum of its proper divisors (37652496).

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

21272304 is a wasteful number, since it uses less digits than its factorization.

21272304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358 (or 352 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21272304 is about 4612.1908026447. The cubic root of 21272304 is about 277.0797860414.

Adding to 21272304 its reverse (40327212), we get a palindrome (61599516).

The spelling of 21272304 in words is "twenty-one million, two hundred seventy-two thousand, three hundred four".