21530330 has 32 divisors (see below), whose sum is σ = 42048720. Its totient is φ = 7905280.

The previous prime is 21530329. The next prime is 21530387. The reversal of 21530330 is 3303512.

It can be written as a sum of positive squares in 8 ways, for example, as 11689561 + 9840769 = 3419^2 + 3137^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a junction number, because it is equal to n+sod(n) for n = 21530299 and 21530308.

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, 5426 + ... + 8514.

Almost surely, 2^21530330 is an apocalyptic number.

21530330 is a deficient number, since it is larger than the sum of its proper divisors (20518390).

21530330 is a wasteful number, since it uses less digits than its factorization.

21530330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3154.

The product of its (nonzero) digits is 270, while the sum is 17.

The square root of 21530330 is about 4640.0786631263. The cubic root of 21530330 is about 278.1955820526.

Adding to 21530330 its reverse (3303512), we get a palindrome (24833842).

The spelling of 21530330 in words is "twenty-one million, five hundred thirty thousand, three hundred thirty".