21331330 has 16 divisors (see below), whose sum is σ = 38923704. Its totient is φ = 8415360.

The previous prime is 21331313. The next prime is 21331333. The reversal of 21331330 is 3313312.

It can be written as a sum of positive squares in 4 ways, for example, as 11553201 + 9778129 = 3399^2 + 3127^2 .

It is not an unprimeable number, because it can be changed into a prime (21331333) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13881 + ... + 15340.

Almost surely, 2^21331330 is an apocalyptic number.

21331330 is a deficient number, since it is larger than the sum of its proper divisors (17592374).

21331330 is a wasteful number, since it uses less digits than its factorization.

21331330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29301.

The product of its (nonzero) digits is 162, while the sum is 16.

The square root of 21331330 is about 4618.5852812306. The cubic root of 21331330 is about 277.3358280075.

Adding to 21331330 its reverse (3313312), we get a palindrome (24644642).

The spelling of 21331330 in words is "twenty-one million, three hundred thirty-one thousand, three hundred thirty".