21330613 has 4 divisors (see below), whose sum is σ = 21398220. Its totient is φ = 21263008.

The previous prime is 21330607. The next prime is 21330629. The reversal of 21330613 is 31603312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1456849 + 19873764 = 1207^2 + 4458^2 .

It is a cyclic number.

It is not a de Polignac number, because 21330613 - 2⁵ = 21330581 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330313) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33328 + ... + 33961.

It is an arithmetic number, because the mean of its divisors is an integer number (5349555).

Almost surely, 2^21330613 is an apocalyptic number.

It is an amenable number.

21330613 is a deficient number, since it is larger than the sum of its proper divisors (67607).

21330613 is an equidigital number, since it uses as much as digits as its factorization.

21330613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67606.

The product of its (nonzero) digits is 324, while the sum is 19.

The square root of 21330613 is about 4618.5076594069. The cubic root of 21330613 is about 277.3327206530.

Adding to 21330613 its reverse (31603312), we get a palindrome (52933925).

The spelling of 21330613 in words is "twenty-one million, three hundred thirty thousand, six hundred thirteen".