21330504 has 72 divisors (see below), whose sum is σ = 62591490. Its totient is φ = 6559488.

The previous prime is 21330503. The next prime is 21330581. The reversal of 21330504 is 40503312.

It can be written as a sum of positive squares in 3 ways, for example, as 4536900 + 16793604 = 2130^2 + 4098^2 .

It is a tau number, because it is divible by the number of its divisors (72).

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

It is not an unprimeable number, because it can be changed into a prime (21330503) by changing a digit.

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 17 ways as a sum of consecutive naturals, for example, 11292 + ... + 13044.

Almost surely, 2^21330504 is an apocalyptic number.

21330504 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 21330504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31295745).

21330504 is an abundant number, since it is smaller than the sum of its proper divisors (41260986).

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

21330504 is a wasteful number, since it uses less digits than its factorization.

21330504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1791 (or 1771 counting only the distinct ones).

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

The square root of 21330504 is about 4618.4958590433. The cubic root of 21330504 is about 277.3322482596.

Adding to 21330504 its reverse (40503312), we get a palindrome (61833816).

The spelling of 21330504 in words is "twenty-one million, three hundred thirty thousand, five hundred four".