21305304 has 48 divisors (see below), whose sum is σ = 57915000. Its totient is φ = 7075584.

The previous prime is 21305293. The next prime is 21305309. The reversal of 21305304 is 40350312.

21305304 is a `hidden beast` number, since 2 + 130 + 530 + 4 = 666.

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 (21305309) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35632 + ... + 36224.

Almost surely, 2^21305304 is an apocalyptic number.

21305304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21305304 is an abundant number, since it is smaller than the sum of its proper divisors (36609696).

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

21305304 is a wasteful number, since it uses less digits than its factorization.

21305304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1104 (or 1097 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21305304 is about 4615.7668918610. The cubic root of 21305304 is about 277.2229911654. Note that the first 3 decimals are identical.

Adding to 21305304 its reverse (40350312), we get a palindrome (61655616).

It can be divided in two parts, 21305 and 304, that added together give a square (21609 = 147²).

The spelling of 21305304 in words is "twenty-one million, three hundred five thousand, three hundred four".